if you want to use your own True Type fonts in your app you can easily do that.
Just add your font file(s) to the resources and insert an array into your Info.plist with the paths:
You can then use these fonts in the SPTextField the same way you use the system fonts: by using their name.
If you don't know the name of a font: double click on the ttf in the Finder to open it in FoontBook and look at the title of the window.
I couldn't find anything in the forums about this, so I thought I post a note here in the hope that it might be helpful for somebody.