Hi Elana, 

Great question! We don’t have a direct way to add new fonts from your fontbook, but getting custom fonts to work is definitely something that is possible, and luckily we have an awesome support article to help you out:http://documentation.unbounce.com/hc/en-us/articles/203510114-Adding-and-Editing-Text#content4. I’d highly recommend taking a look. If you still have questions after going over the article, email us directly so we can dive into your pages and lend you a hand (support@unbounce.com). 

Hope this helps!