You can also point to font files with @font-face. I use a small custom font that's only 16 KB. Although, when opening the file locally, you have to first disable local file restrictions in safari's settings before it works...

  <defs>
  <style type="text/css">
  @font-face {
  font-family: 'A-font';
  src: url('A-font.woff') format('woff');
  font-weight: normal;
  font-style: normal; }
  </style>
  </defs>