Hi besid54, Again not familiar with your particular radio model 7C but it seems like the only RTH function that may be possible on your radio is RTH via a Switch. That would mean that if you fly out too far and lose radio communication your quad may/will not come back to launch location.
I know accessing your "Prog. Mix" menu may be different and so will the switch you decide to select to perform this function.
The following is how to set RTH on demand via switch on a T10C*G and it is only a rough guide for you.
On the 10C RTH on demand only works if the radio is set to GPS flight mode.
Other Futaba radios like the 8FG super can be configured so that RTH on demand functions regardless of flight mode (manual, Atti or GPS-Atti).
Return to Home on Demand (under Prog. Mix1-8 menu) :-
This will only work if (SwE) (Flight Mode switch) is in the Down position (GPS Position Hold).
To get to “Prog. Mix1-8” menu highlight MODEL and press the mode button.
1. Press the “Push” button and then select/highlight Mix number one, press the “Push” button again, scroll down to Master-Slave and select “CH7” on both.
2. Go to “SW” (switch) and select “SwD” (switch D) then go to “POSI” and select “Down”.
3. Go to “RATE” “H” and set this to -50% (highlight “H” by moving SwE to Down position).
4. Test by moving switch to up/down position and test within DJI Assistant.
Regards - bruce