I know it is not allowed to measure on Shabbat. If one wants to get a general idea of quantity to try to not to have too much, is it acceptable to first to put it into a cup to get the rough amount (e.g. 8 oz) before putting it on the plate or better to just eyeball it?
As long as your are not measuring it exactly, but using the cup as a way to apporximate, it is permitted and not considered measuring on Shabbos.
Have a good Shabbos
Rema O:CH 323-1