Skorupski's conception of practical agency requires a correlate to the epistemic notion of self-audit and is found in the view of an agent grasping, from a first-person insight, grounds for action. Skorupski also relates epistemic self-audit to recognition of what Parfit pictures as intentional objectivity regarding some form of such recognition as part of what provides us with a warranted reason for action. Skorupski puts this by saying that what one has reason to believe depends on the set of facts one apperceives.
If knowledge of such apperceiving of facts takes place at all then there must be a similar warranted apperception of norms. This latter gives Skorupski his picture of practical autonomy but what distinguishes it from the view of autonomy that is central to Kant is that it is not pictured primarily in relation to moral norms but practical norms of any kind (hence taking hypothetical imperatives to have the same relation to autonomy as categorical ones).
Skorupski's general conception of reason allows for evaluative reasons to be distinct from epistemic ones but he does not join Kant in picturing reason as a general ability. One of the bases of Skorupski's departure from Kant here is that he is committed to a radical kind of pluralism about the different kinds of reason though he still thinks that reason relations have an epistemic and ontological unity which arises from our autonomous capacities. Given this latter point it is not that clear why Skorupski denies validity to a general claim about "reason".
When it comes to practical reason in general Skorupski builds out from the notion of "warrant" indicating that norms give warranted reasons for action only when combined with warranted beliefs about one's desires. In making this claim Skorupski builds in a kind of sentimentalism which is part of what he means by referring to "evaluative" reasons. On Skorupski's view what there is reason to do can depend on what there is reason to feel, something that invokes his idea of the "Bridge principle" which is stated by him as follows:
Bridge says that there is reason for x to do what the affective responses that there is reason for x to feel would characteristically dispose x to do (24).
Part of the point of this is apparently to reduce the "gap" between reason and sentiment that Kant introduces though a lot here depends on the nature of the feelings invoked. Kant is far from outlawing reference to feeling in practical evaluation despite the popular picture (one encouraged to a degree by the argument of Groundwork I). But feeling is nonetheless distinguished for Kant between practical and pathological, a distinction that can also be understood to refer to a difference between justified action by reference to feeling and unjustified action by reference to feeling (with the latter requiring the subordination of reason to "passion"). It remains to be seen whether anything like this distinction can be built into Skorupski's account of practical reason.
Skorupski distinguishes between two distinct kinds of sentimentalism making clear that he is not a sentimentalist with regard to practical reason as this would entail that the Bridge principle was the only principle of practical reason. A basic reason why Skorupski is not a sentimentalist with regard to practical reason is that he admits an important place for appeals to impartiality. Skorupski also understands the agent-neutrality that is involved in universalist forms of morality (including Kant's) as requiring a form of impartiality. However, whilst Skorupski thinks that the need for some kind of appeal to impartiality is a requirement for a full theory of practical reason he departs from Kant in terms of not taking the categorical imperative to be the foundation (or "supreme principle") of morality. In assuming that universalism is effectively the same as impartiality Skorupski also makes a large step towards equating the Kantian view of universality with a consequentalist one.
Skorupski's sentimentalism is partially justified by his account of blame where blame is understood as a sentiment that it is right to feel. So Skorupski, whilst denying sentimentalism concerning practical reason adopts it with regard to morality. Again this is partly due to his view that the type of impartial appraisal he wishes to allow for concerns a relation to the Good (rather than the Right).
Skorupski's departures from Kant in the area of practical reason thus are partly due to a failure on Skorupski's part to see the place of feeling in Kant's view of practical reason and partly due to a simple conflation of universalisation with impartiality (and of the latter with an implicit consequentialism). But it is also true that Skorupski wishes to motivate a conception of feelings as having an immanent rationality that is specific to them, a rationality that is part of the sense of them as having an internal intentional objectivity. So Skorupski wishes to extend the area of spontaneity so that it encompasses feeling but doesn't see that so doing requires an internal relation of feeling to reason as he thinks of reason as always immanent to the area in question.