Unfortunately, Rapid Resizer doesn't support using fonts from your computer.

Basically, the font has to have an SIL/OFL or Apache license.

The fonts in the list directly at http://www.fontsquirrel.com/fonts/list/find_fonts?filter%5Blicense%5D%5B0%5D=open

Then notify us, we will add the font(s) if the license is acceptable.