I think it was two pounds I did for a 2.5 gallon batch, and it was way too much for me. Could definately taste the fruit, it wasn't subtle at all (didn't help that the beer had a very low gravity). I heated the fruit to ~170 degrees for ten minutes to both pasteurize and break down the cells - this aspect of it worked very well. The frozen ones will already have the cellular walls broken down, so I'd use those, pasteruize them, add them to the secondary. You may want to consider doing a tertiary (sp?) fermentation, give the fruit particles an extra chance to settle out (getting a piece of raspberry in your beer is not pleasant, it has the texture of a loogie).