Since dog foods are not all made the same you should go by the amount listed on the package/can. Some foods go by size others by breed. Also you should take the recommended amount and break that up into three feedings a day as small dogs are more prone to have a drop in blood sugar if they go without food for long periods. You can also add some green beans in with the meal as they are healthy and not fattening. She may get filled up more with these added.