Souring a "normal" beer

Short of a "lambic" style, what would be the best ways to sour up a very strong fruit flavored beer.
I am looking at 5-10# of raspberries in a 5G batch of basic wheat beer. I want a pretty strong sweet/tart character. Acidulated malt has been suggested as has Lactic acid. Not even sure what PH numbers I am looking at.
Does one add the acid at bottling, to taste? Is it like an eye-dropper full to take it down half a point?

Just yesterday (I think it was) someone was talking about having a very tart beer after adding raspberries to secondary and needing to add some sweetener. So, I think that fermenting out the raspberries will give you a very sour/tart flavor without adding any souring.

If you want to add lactic acid or acidulated malt, that's usually done in the mash. You could add some citric acid at bottling, though, I'm sure.

I think I've read you can add lactic acid after fermentation is complete also - if you want more sour/acidic character. I think citric acid can work the same way as yooper stated.

I've only added acidulated malt during mashing and was pleased with the result. I'm also pretty sure that acidulated malt is just malt containing extra lactic acid due to specialized malting processes. Thus it makes sense it could be a similar effect to using lactic acid alone.