I have a .TTF file but with the “O” icon that an application in Windows 98 does not see. Is it possible to change this font to a .TTF that has the TTF icon? I gather from reading other posts it is possibly to do with the digitally signed part of the newer TTF file.
It is most likely an OpenType font with CFF outlines. Just open it with FontCreator 6 and save it, and the font is then converted to a OpenType font with TrueType outlines that is accepted by Windows 98.