We try to avoid using additional custom fonts as much as possible as it might break the template’s default layout and responsiveness. Each template already has their own 2-custom-font combinations (a serif and a sans serif type) which you can use interchangeably between headings and content.
If you really need to use a custom font, we’ll let you use one but only through Google Fonts https://www.google.com/fonts – that means the font you want to use should be available there. This is to minimize page load time as well as avoid rendering issues and incompatibility with the default styling.
Let us know how you’d like to go about it.