Generating F(n) keys with SU-8W

[david.hagood at gmail.com (david.hagood at gmail.com)]

I just bought a Nokia SU-8W keyboard for my N800 and N770, and have it
paired up with the N800, but I cannot figure out how to generate an F(n)
key - e.g. I cannot figure out how to generate a CTRL-F4 to close a
window.

I've tried CTRL-Fn then key, Alt-Fn then key, Fn+key, to no avail.