Getting what error? You don't register functions in SilkTest. You just need to make sure you the .inc file is being compiled. You can specify a 'use' statement in your .t file or create a frame.inc file and make sure it's listed there. Then specify the frame.inc file in use files field in Runtime options.
Have you ever noticed? Anybody going slower than you is an idiot, and anyone going faster than you is a maniac.
registering a function has to do with the functions created using the Extension Kit. If you are getting an error that a function has not been registered, it means that the app that you are testing is failing to load the extension