RtTimerCreate ????

I am trying to setup a RtTimer on my PhAB. My question is, how do you setup the third parameter which the timer calls when it times out.
Can I just put the callback function name?

RtTimer_t *RtTimerCreate( clockid_t clock_id,
int prio,
RtTimerCbF_t *cb,
void *data );

Yes, but make sure it is of the right type (same arguments )

I can not seem to find any documents on RtTimerCbF_t type. How can I make a callback function with this type?
Just make normal function name “func1” and passing it to the 3rd argument as (RtTimerCbF_t *) func1 is the correct way? or do I have to create a sepecial variable with RtTimerCbF_t?