The description of Caps states "Draw your own typographic characters, import desktop fonts, kern and preview them", but I can't for the life of me find the import feature?
We've held back this feature while we improve it; reading font metrics is a bit hairy, and we want to make sure it works reliably. It should be available in the future!
In case anyone else find this thread, here's a tool that fills this void for now!
There's also a web tool here Font conversion on mac - #5 by timhei