Here is a method I use that works every time. The below is scaled for a 5 gallon batch. It can be scaled up or down depending on your volume of beer.
After fermentation is done and any dry hopping, cold crash the vessel in a refrigerator (40F-33F) for 24 hours. A chill haze should be evident.
Bring 1 cup of water to boil in a microwave
Let the water cool back down for 15 minutes (I just leave it in the microwave)
Add 2.5 grams of knox gelatin
Stir in thoroughly to dissolve. Do not reheat! It can take a couple minutes of vigorous stirring to get it to all dissolve.
Pour the warm dissolved gelatin solution into the cold crashed beer. Swirl the vessel a couple times to start the mixing. Thoroughly mixing is not necessary. Close the vessel and let it sit in the refrigerator for another 24-48 hours. You will know it is done because the chill haze will be gone.
Rack to bottling bucket and proceed as normal for bottling. It might take an extra week to get fully carbed, but otherwise the moderate loss of yeast from solution is not a big deal.
I have seen methods that use up to 4grams of gelatin per gallon. I find that 0.5g/gal works just fine. I tried 0.1g/gal and that does not work. I have not bothered to titrate between those two points.
