How to add fonts in 3.0

The app refers to supporting fonts present in the app's document folder.

But how do you get a font into the app's document folder? If I email myself an EPUB I can open that in (copying it into) Marvin 3, but if I email myself a TTF there's no option to open that in Marvin 3.

The selection of included free fonts is a nice touch, BTW.