You can track your ads by giving key code for different ads in different sites. For example if your SFI Gateway is like http://www.sfi4.com/111111.2222/FREE where, 111111 is your SFI ID and 2222 is the key code. You can give different key code numbers for different sites and note down the numbers for each site. When you get sign ups the key code will be shown with each sign up.