The RTH function comes ready. In fact, there is no where that you can set with NAZA assistant but the IOC that you must set because it came unchecked as default. But there are conditions that must be fulfilled before the RTH can work properly. First when you plug in the battery and during the "warm up" period, once the 6 or more satellites are detected, you will see the rapid GREEN indicating that the home position is locked. This is the spot where your Phantom will return to. Next during the course, all 6 or more satellites have to be locked in at all time or the RTH will NOT work. The GPS mode is not relevant simply because the RTH is activated when the Phantom lost the communication with the transmitter.
As for the IOC:
The CL works via the compass so no GPS required so no need to set the GPS mode.
The HL required GPS mode. But both CL & HL require the home lock position recorded either 30 seconds during the warm (rapid GREEN) up as mentioned above or set the home lock position yourself as follows:
To do a manual CL recording I toggle from off to CL 4 times
To do a manual HL recording I toggle from CL to HL 4 times
