Symptoms

When adding the K2 app to SP list or library and creating the forms, I get a new item or new document form and view created, but I cannot select the K2 new document form from the Forms Settings screen in the app. This option is always grayed out? How can I configured a document library specifically so that I can use a K2 form for the new document process?
 

Diagnoses

Confirmed that this is by design.
 

Resolution

This is as designed to see the 'Create new Item, use...' setting in the Manage Form Settings screen, as disabled. It is disabled because it created confusion that the user assumes on the Form Settings Page for a Document Library - that K2 will provide the option of using a New Form - which is not the case.