for 50g you take 1 teaspoon of glycerin ... for just 1 bowl its difficult
but i wouldnt put glycerin to al fakher ... you will get strong headaches, if you do this! glycerin is good for dry tobacco, but not for wet tobacco like al fakher ... dont do this! you will destroy the tobacco and maybe also your health ..
and btw: the clouds wont be bigger than with normal al fakher ... i tried many things with glycerin and also with molasses. believe me that this is a bad idea ...
to get bigger clouds of smoke, try to use more tobacco, less foil or more coals, to get more heat!