[phossler]

I use the editor to add the file(s) to the epub and add this this CSS

@font-face {
  font-family: "Charis SIL Compact";
  font-weight: normal;
  font-style: normal;
  src: url(../fonts/CharisSILR.ttf);
  }
@font-face {
  font-family: "Charis SIL Compact";
  font-weight: bold;
  font-style: normal;
  src: url(../fonts/CharisSILB.ttf);
  }
@font-face {
  font-family: "Charis SIL Compact";
  font-weight: normal;
  font-style: italic;
  src: url(../fonts/CharisSILI.ttf);
  }
@font-face {
  font-family: "Charis SIL Compact";
  font-weight: bold;
  font-style: italic;
  src: url(../fonts/CharisSILBI.ttf);
  }
body {
  font-family: "Charis SIL Compact", serif;
}