Add font to bootstrap sub-theme
I followed this guide on Google Fonts to get it to work with my downloaded font. In your case that would be editing your info file to declare that you have fonts assets:

name: Subboot
description: Bootstrap Subtheme
type: theme
base theme: bootstrap
core: 8.x
libraries:
  - subboot/fonts


then edit the libraries.yml in your subtheme, ex. subboot.libraries.yml to add in the following:

fonts:
  css:
    theme:
      //your.domain.com/path/to/font {}