Installing a new TTF font on a MAC is easy by simply following the steps show below.
1) Download the True Type Font file (ttf) and open it in the Finder. Right Click on the file and Choose Open with Font Book.
2) Doing so will open a window that will display the Font letters and on the bottom right there will be an Install Font Button. Click on it.
3) Finally Font Book will verify the Font file and if all is well, the font will be installed and you can see in the Font Book as shown below. Now this font will be available into any programs that uses fonts.