In TTerm for iPad 1.1.0 and above key mapping allows emulation Function (Fx) and Programmable Function (Pfx) keys to be mapped elsewhere, typically emulation F1 to F10 is mapped to Command + 1 through Command + 0 on your bluetooth keyboard and F11 and above is mapped to Command + Q (directly below the 1 key) and so on.
Due to restrictions in iOS concerning which keys TTerm for iPad can directly access, physical function keys are not supported on bluetooth keyboards.
The key mapping function in TTerm for iPad can be found be tapping Edit configuration > keyboard > bluetooth keyboard. Here you will be able to list the emulation keyboard function keys and their bluetooth key equivalents. If these defaults mappings are not to your liking they may be altered.
Listings of the default keyboard mappings for each individual emulation are provided elsewhere in this FAQ.