I've used honey malt quite frequently in pale ales, ambers, & wheats (partial mashes with +/-8lbs of grain and 2-4 lbs DME) . The reviews have all been positive. I've used anywhere from 8 oz to 2 pounds. It WILL add sweetness to your brew, so I tend to add a little more hops to balance it out. For a raspberry wheat, I'd probably throw in 2 pounds, but I like the malt & balance it with hops. Try a pound; I think that it will really compliment the style. You can always add more/less the next time, but with that style I think that a pound is pretty safe.
As with any ingredient until you use it and see how you like it, it's really just a guess. However, it won't turn your brew into turpentine; just add a honey-like sweetness.