The F-keys aren't documented for DOpus.SendKey() and @sendkey. Are even more keys available that also aren't mentioned?
Do you mean you've tried it and it works but isn't documented, or that you want it to work but it doesn't?
I tried f1 and shift+f10 and both of them work. I'm assuming the rest of the F-keys also work. This is currently just an undocumented feature.