Some Wordfast keyboard shortcuts use keys that are not found on some Mac keyboards. However, Macs usually let you combine the Function key with another key to produce the missing key. Here is a list:

   Home = Fn + ←

   End = Fn + →

   Insert = Fn + Enter

   Delete = Fn + Backspace

So if you want to use, for example, the Alt+Delete keyboard shortcut, you actually need to press Alt+Fn+Backspace.