Humanity and personality - what, for Kant, is the source of moral normativity?

According to Korsgaard's very influential interpretation, moral normativity follows from a commonly accepted conception of rational agency, namely, the capacity to set ends and pursue them or humanity. The paper argues that humanity is not the source of moral normativity. Taking the exercise of your freedom in pursuit of your ends to be justified commits you to acknowledging the equal claim of others to see themselves as justified in the pursuit of their ends. This entails the equal restriction of the freedom of each to ensure maximal freedom for all. But this is precisely what Kant thinks of as the state of right. In contrast, the paper claims that the second formula of the categorical imperative commands making the humanity of rational beings who are assumed to possess the capacity to act morally or personality, into our end, precisely because they are assumed to possess this distinct rational capacity.