I have received a few requests to add support for LinkedIn. While I don't have the time to add official support for LinkedIn at the moment, I have put some of my existing code on GitHub.
The solution of Skybrud.Social now has a separate project for LinkedIn called
Skybrud.Social.LinkedIn. The implementation is still very limited, but should take care of both OAuth 1.0a and OAuth 2 authentication. The project isn't released anywhere, and I won't be adding any documentation for the time being.
You can also read (just a little bit) more about LinkedIn support in this GitHub issue: