If the user has osx 10.3X he can use the .ttf fonts.
The one thing to be VERY careful about is to NOT replicate truetype fonts that came with, or were later installed on, the mac. You do not want 2 different copies of Arial, Times New Roman, etc.
It's easiest to just transfer the necessary fonts to the mac - let's say to a new folder on the desktop. If you double click on a font in that folder, it should launch Fontbook and ask if you want to install. If, by some chance, you can't get that to work, laucn Fontbook from the Applications folder, navigate to the font and install. Fontbook will at least tell you if multiple copies of that font are insatalled and active.