IMPORTANT: This guide requires that you have your own Typekit.com account which is a paid service available from Adobe. If you want to add other fonts to your site without this you might consider using Google fonts guide here
You can use Typekit fonts on your OptimizePress pages with a little custom code.
Once you have these codes you can add them in the Other Scripts > Custom CSS / Header sections as shown in this screenshot:
Remember: You don't have to use your new font for all classes on your pages - you can be selective in which classes you affect with your new font. E.g. if you just want to affect headlines on your pages you might use: