Witbier spicing...at bottling

If you have a stirplate get some vodka into that flask. Get your spices in the vodka and get something liquid that you can add with your priming sugar. It's really too late in the game for a 'dry' addition. If you add orange peel, I suspect your stir bar won't work anyway. Make an extract and shake the crap out of it intermittently. Taste it before you add it to your bottling bucket. It should be pretty strong, but not boozy. Try to use as little vodka as possible.

Edit: You should be very generous with the spices. You don't have to add ALL the extract. AT LEAST 2tsp nutmeg, corriander, and a heavy dose (1.5-2.0 oz of orange peel. Sweet would probably be kinder in the vodka).

 

eh I wouldnt use nutmeg in a wit, but I think the beer could be just fine as is without anything added. if you used a good yeast (WY witbier) then it will be good on its own. If you really want to add some citrus I would suggest bringing some fresh orange wedges instead. This is an easier fix and you dont have to worry about possibly over-spicing something when you wont find out till its too late and people are drinking it

 

You can try making a "spice potion".

2 cups high-proof vodka (nothing too expense)
1/4 oz. of orange zest (zesting fresh is way better than the packaged dried peel)
1/4 oz of whole cordiander, lightly crushed (toast the whole spiced in a dry pan for a few seconds to bring out more nuttiness)
1/4 oz of bright, citrusy hops (because why the fuck not)

Mix it all in an air-tight jar and let it sit at room temperature. When you're ready to bottle, you can strain the solids out of the vodka and add it right to the bottling bucket. Use it sparingly, though, as it will be potent stuff. I suggest siphoning 1 oz. of beer into a glass, then using an eye-dropper to add the exact to the glass, a drop at a time. When you find the right amount of spice, you could do the math to figure out how much you need to add to the whole batch for the same effect.

OR

If you're not feeling so precise or intense, you could just boil your priming solution, then when you turn the heat off, add 1/4 oz. each of fresh orange zest, powdered coriander, and hops, and let the whole sit for 20 minutes or so to extract the flavor. It'll be like adding a spice tea to your beer.