Ron Natalie wrote:
There's no need to tell the other pilot to be "PIC", just ask him
to take the controls. There's a difference betweeen operating the
controls and serving as pilot in command.

My recommendation would be to brief your safety pilot before you start
up so you both know what you're expecting from each other. When you
break out on short final is no time for the two of you to be wondering
why the other guy doesn't appear to be doing anything about getting
ready to land (or worse, one guy is pulling the throttle back to land
while the other guy is picking the gear up to go missed).