Here is how to add a .ttf font in Ubuntu.
Open a terminal and change to the directory that contains the font:
Example: cd /home/username/Desktop
Copy the file to /usr/share/fonts and rebuild your font cache:
cp font_name.ttf /usr/shar/fonts/font_name.ttf
sudo fc-cache -f -v
The font should now be installed and available in your applications.
