RTO
In the airline I am familiar with, it used to be the case that the Capt made the RTO call and the PF, whichever that was, carried out the stopping actions.
It was found that a better RTO resulted when the Capt made both the call and took control to do the RTO actions.
The F/O then was PM for failure drills etc.
Not very familiar with any other system, so I can't comment whether this is the optimum scenario or not. Hope this helps.