How to map RC channels to custom servo

I am conducting fixed-wing ground heading control experiments.I want to map the RC channel to the steering wheel channel just like flap,what can I do? I can set steering wheel like RC_MAP_FLAPS directlyThank you .at the same time,I want to use actuator_servos to control steering wheel by offboard mode ,so I can’t use RC_AUX1.

Usually, the wheel has the same output as the yaw. So you can select a rudder for your wheel.

Maybe re-write your question. It looks like your lines are strangled.

Thank you! But my plane has rudders.I want to map RC channels to other servos like steering wheel servo and Brake system servos

Add new RC channel in your radio, that should appear in your radio calibration tab in QGC.
Select that RC channel for the required servo in PWM AUX or MAIN.

Thanks!To select that RC channel foIr the required servo in PWM AUX or MAIN is not meeting me need.I want to use topic actuator_servos to control it so it must be a servo.