Mac OS X saves fonts as .dfont (Data Fork Font) files, while Windows typically saves them as .ttf (True Type Font) files. A Mac font can be used on the Windows operating system if the font file format is converted, which can be done easily with the right software. Both free and paid font applications exist; free options are best for one-off conversions, while paid applications make sense for those who will frequently convert fonts across systems.
Using DfontSplitter (Windows or Mac)
Transfer your .dfont file to your Windows operating system.
Download and install the Windows version of DfontSplitter (see Resources). If you only have access to Mac OS X and are converting the font for someone else, install the Mac version. All the following directions remain the same for both operating systems.
Click "Add File" and navigate to the folder where your .dfont file is located.
Double-click on your .dfont file to select it.
Click "Browse" and navigate to the folder where you want your .ttf file saved. The desktop is a good, easy-to-locate choice.
Click "Convert." Your new .ttf file will appear in the location you specified.
Use fondu on Ubuntu (Linux)
Transfer the .dfont file to your Ubuntu system using scp or FTP.
Install fondu by typing:
sudo apt-get install fondu
Move into the directory where your .dfont file is located:
(Replace /path/to/file with the specific path to your directory.)
(Replace file.dfont with the specific filename of your .dfont file.)
Move the newly-created .ttf file into your ~/.fonts directory:
mv file.ttf ~/.fonts
(Replace file.ttf with the specific filename of your .ttf file.)
Use TransType (Windows)
Download and install TransType (see Resources).
Launch TransType, then drag your .dfont file into the left-hand column.
Expand the font file by clicking the "+" sign to the left of the font name. Click the font name that appears on the next line to highlight it.
Click the down-facing arrow to the right of the destination filename in the right-hand column. Select "MS Windows 1252 Latin 1" from the drop-down menu.
Click "Convert." A dialog box will appear.
Select the directory to save the .ttf file in by clicking on it. Click "OK."
Use email (a zipped file is best), a USB stick or FTP to transfer the .ttf file from your Mac to your Windows system.
It may be easiest to install conversion software on Windows and move the .dfont file to Windows before converting it to .ttf.