How to add a font file into AutoCAD for Windows
AutoCAD supports SHX and TrueType fonts.
Installing an SHX font:
Copy .shx files into the Fonts folder within the AutoCAD program folder:
C:\Program Files\Autodesk\AutoCAD 20xx\Fonts
Note: PostScript fonts (.pfb) and shape files (.shp) can be converted to .shx by using the COMPILE command in AutoCAD.
Installing a TrueType font:
AutoCAD reads TrueType (.ttf) fonts that are installed in the operating system. TTF files do not go into AutoCAD's own Fonts folder. Copy .ttf files into:
C:\Windows\Fonts
As an alternative, you may right-click a .ttf file and choose Install.
Note: Windows XP and Vista systems require going to the Control Panel and opening Fonts and then using "Install new font" under the Font menu.
How to install a font into AutoCAD for Mac
AutoCAD for Mac supports SHX and TrueType fonts.
Fonts are added to AutoCAD for Mac into the application package. This is strictly required for SHX fonts but TrueType fonts can be installed normally via Font Book instead of being put into AutoCAD. This way the TrueType font(s) can be used by all applications on the system. To add a font to AutoCAD:
1. Quit AutoCAD.
2. In the Finder, navigate to /Applications/Autodesk/AutoCAD 201x.
3. Right-click the 'AutoCAD 201x.app' and pick Show Package Contents.
4. Go into /Contents/Resources/Fonts.
5. Copy your font file(s) into either the shx or ttf folder, depending on the type of font it is.