When I have a sitter take care of my tank, I portion out the amount of food each time the sitter to feed the tank. In fact, for anything add to the tank, I specifically portion the amount, or specifically ask them to give an specific amout. This prevent a lot of disaster, especially if you ask a non reefer to take care of your tank.
I even show them exactly how to clip the Nori on the holder.
I mark the water level and if need how much water to add (in the event that my auto top off not 100% correct). I don't use a level control top off but an an adjustable continuous pump to add Kalk.
Too compulsive you said? No, not at all. What is common sense to us is not at all common send for another person.