First, what is her size in relationship her age and to her parents? Do you expect her to be tall? Is she short waisted and long legged, or visa versa? Is she stocky or a toothpick? You basically have two choices at this age, buy a kid's saddle that she will outgrow in a couple of years or get a saddle she will grow into. How fast and how big she will grow may be a factor here. Many kid's saddles are poorly made and do not have a balanced seat that helps a rider keep her leg underneath her body. Most of the youth riders I see riding in kid's saddles are way too big for the saddles. As for the size of the saddle, two things you want to consider in fitting the child: seat size and leg position. If the child is a toothpick, she will be floating around in the seat of an adult or large youth saddle. On the other hand, a child of average size will quickly fill the seat of a kid's saddle. There should be room in front of and behind a rider's seat, the cantle should not touch the back of her seat. You also need to consider the fit of the saddle to her leg. The stirrups should adjust so that they can wrap around her leg and twist. If they have to be adjusted too short, they won't want to wrap around her leg and she'll be constantly struggling to keep the stirrup on her foot. If the stirrups have to be adjusted really long, she won't be able to benefit from the contact with her leg on the fenders. Most importantly, make sure the saddle has a balanced seat. You can tell this by looking at the profile of the saddle as it sits on a stand. The stirrups should hang straight down, beneath the seat. If they stretch forward, it is not a balanced saddle and will impede her riding. You can look at any catalogue that has a number of Western saddles and see that some saddles are balanced and some are not. Some saddles will actually be advertised as being a balanced ride and this is critical to developing proper equitation. Of course, the saddle also has to fit the horse reasonably well and if your horse is stocky, a child's saddle probably will not work too well. My guess, after having said all this, is that you're on the right track and that a 14" adult saddle would be about right. This might be referred to as a Lady's saddle or a youth saddle. Good luck! Your daughter is lucky to have a father so interested in her riding endeavors!