Nettie, you buy the powder from a health food shop and mix a little (less than 1/4 tsp) with breast milk and feed it via a spoon to the baby. (all sterilized stuff of course) it should be semi-liquid enough for the baby to get it down without difficulty. it was trial and error here.

Because of its action, baby has to take it, not the mum. It works to "sop" up acid and kind of thicken the milk in the stomach, also settles things. Babies on formula, who have reflux, can get a "thickened" formula to keep it down. This is the bfing equivalent, I guess.