About RC_OPTIONS and operating relays

Hi there,
I want to use the gpio pins on the pixhawk board in order to operate some custom lights of our vehicle. I know that I should set the RELAY_PIN and BRD_PWM_COUNT parameters accordingly in order to use gpio but I couldn’t find an example on operating relays in ardusub documentation. I know that I can use them using manual control btn functions but I also want to use them with RC_INPUT.
In the documentation, I found out some parameters related to RC_OPTIONS and I wonder how can I use them for relays? There is an option called Relay1 on/off but rc channels take pwm inputs as far as I know so how can I use it as on/off? I would like to operate both servo and lights using RC_INPUT if its possible.
If its not possible to operate relays using rc_input, can you send me some example code to operate relay?