If you are subscribing to the country lookup service, you will use this page to determine how much you will credit members according to which countries visitors are from.
The reason you want to do this is because the adservers that are financing your ptp page for you generally pay one of two ways: They either pay only for visitors from certain countries (usually the same countries as search engines do), or they pay more for visitors from some countries than others.

A good example of the latter can be seen on the FAQ page at PayPopUp. Scroll down to the tables that show the pay rate for various countries. If a member promotes their ptp page to a largely chinese audience and you are paying 60 cents per 1000 credits (including China), you can see that you may lose money instead of making a profit!

This is why you want to pay different rates for different countries. The Country Lookup Service will enable you to do this, thus maximizing your profit margin.

After you have determined which group to place each country in using the bottom table, decide how many credits you want to pay members for visitors from each country group.
You can use fractions here. For example, you may want to pay 1.5 credits for group 1, 1 credit for group 2, and so on down to 0.25 credit for group 5. (Or use whatever amount you choose for each group).
After setting your rates, click the submit button.

Update credit rate for groups

Default rate is used when country cannot be determined