My experience with use of external fonts.
The file of your font is for example fontExt.ttf
In Windows XP it goes under Windows/font.

How you declare your font in lite-c:
FONT* my_font = "nameMyFont#40";
Where nameMyFont is the name of your font under Windows/font, not always is the same of name of starting font file.
This last thing is very very important.
The dimension of character is 40 in the example.
Best Regards
frank58