I personally prefer to add priming sugar to the entire 5 gal batch. I used to boil the entire 5 oz packet in a cup of water and add it while transferring to my bottling bucket, but some of my beers were over carbonated (if you weigh those packets some are more then 5 oz some are less). Now I use John palmers Nomograph to determine a more accurate amount of priming sugar to use. Here's a link.
Primary: Belgian Chocolate Stout
Bottled: Pumpkin Ale, Cinnamon Toast Crunch Milk Stout, Captain Morgan Oaked Black IPA, Brandon O's Graff, Gingerbread Spiced Brown Ale, Honey Bacon Ale