Depending on how big you want your bait site to be you can use anywhere from 1/4 to about 1/2 of a bag of corn. Don't go "hog wild" (pardon the pun) initially until you find out which sites are getting hit. We have a couple on the ranch I lease that the hogs just never seem to hit and a couple of others that they just destroy.

The red soda (I believe the name is something like Big Red) is just a cheap nasty cherry flavored sugary soda that leeches into the surrounding ground making it irresistable to the hogs. Even if there is no corn in the dirt they will often root around and tear up the areas that the soda soaked into. They smell it and associate it with food.

I also think that in the hot sun as the water in the soda evaporates it carries the scent downwind.

When the hogs do finally find your bait site it will look like sombody was using a backhoe to dig a hole.