How can I use a font from TypeKit?

On Typekit's website, they give you a block of "embed" JavaScript code for a given font they tell you to copy into your website.

So within the theme options in the WordPress admin, under  Theme Options > Styles > Typography, for a given font, you'll select "Typekit Font", and then just fill in the relevant fields that appear. The Font Family will be the name of the font, and the embed code will be that chunk of code Typekit gives you and tells you to paste in your website.