If you're going to add the raspberries to your primary, I would advise against adding them before or during primary fermentation. Do it once primary is complete. This provides two advantages. Firstly, any bacteria you miss in the pasteurization will tend to thrive moreso in a high-sugar, low-alcohol environment, as opposed to a low-sugar, high-alcohol environment. Secondly, the CO2 created during primary is going to wash your berries of a lot of the raspberry aroma you want.
I say this with humility, because I have never brewed a fruit beer before. I'm just repeating what I heard on the TBN's The Jamil Show Episode on Fruit Beer.