Some observations: To go to reverse when starting at a land based airport, I had to press the brakes first. This was also required after pressing Ctrl-F4. When on water let the engine rpm return to idle then press and hold Ctrl-F2 until you see the RPM drop by about 100, then you know you are in reverse. Pressing Ctrl-F4 from reverse prop (when at engine idle) will increase the RPM back by about 100.