My girl is average size. 29 inches and 19.5 lbs, 9 months old.
She does have chunky legs though, but not more than other kids. I've never used the lowest rise for her on any diaper I had, mostly because I didn't cloth right away when she could have fit them because I was still figuring out a 'routine' to my new life.
If your child has skinny legs though I've heard this isn't the brand for you.