Note from Carma @PBI:
The reason why there is aren't any specific measurements for the pork stock is because much depends on the amount of drippings from the roast or chops. The dripping will vary. Within the directions it is noted that you add enough stock, broth, or wine to the drippings to make two cups. So if your dripping from a roast are 1/2 cup, you would need 1 1/2 cups of stock or wine. But if you only had under 1/4 cup of drippings, you would need over 1 3/4 cups stock or wine. My suggestion is to plan for 2 cups of stock or wine and add what you will need to make the 2 cups of liquid.