Adding a font to Upfront

I'm trying to add a bunch of custom fonts to my theme and use them to style the Headers and Paragraphs. We tried the method suggested here https://premium.wpmudev.org/forums/topic/upfront-builder-issue-custom-font-implementation-not-google-fonts?message=support-forums-topic-status-updated#post-1141258 using the @font-face but it didn't work.