AFAIK there are only a few apps that use Truetype such as Wordprocessors (Wordworth) and possibly DTP such as Pagestream 3+.
You can specify where to put your fonts by using assign e.g. ASSIGN FONTS: DH0:TTF_FONTS ADD
with the Add parameter.
You can download fonts from:
http://www.desktoppublishing.com/fonts-free.html
