On a PC: Double click on the OTF or TTF file, then click “Install.” On a Mac: Double click on the OTF or TTF file, then click “Install Font.” Alternately, you can manually install fonts to bypass Fontbook: Copy (CMD + C) the file(s) either OTF or TTF format, then Paste (CMD + V) the files into this folder: HD > Library > Fonts Important: Restart the program where you intend to use the font, and the fonts will show up in your font list when you open the program again.