I used rosewater a year or two ago in a grapefruit wheat and had to go extremely light with it (post boil, in the bottling bucket). Did tests with a dropper and a measured amount of a similar beer...1 drop wasn't quite enough, but 2 was too much for me and my tasting subjects. Ended up with (if I remember correctly, don't have my notes handy) about 1/8 of a teaspoon for a 5 gallon batch. I thought it was good, but others thought it was a little too much. Neat part about it was that no one could definitively say, "That's rose water in there!". They could all tell that there was *something* different, but couldn't place it.