Fly manually in Waypoint Mode.
Then at the time RTH is initiated, press the appropriate button to create a waypoint.
or
Press the appropriate button at the time/position you took the last photo.
You have now created a waypoint mission with 1 waypoint.
Choose “None” as Finish Action.
Save it and run it to resume your manual flight.
The “appropriate button” depends on the type of drone/controller you are using. It can be the C1, C2 or Function Key.