She is so precious Kay, what a cutie! It's tough to tell when they are youngsters what mix they really are. I know when Tasha was a pup, a lot of people thought she had lab in her, but as she grew she got more slim-lined and greyhoundish.
Right now Kiara looks a bit houndish to me, almost more doberman-like than Rottie in some pictures but in others I really see the rottie more. Once she's grown into a young lady it might be easier to make guesses. I know even my vet predicted Tasha would be a 60-65 pound adult but she ended up staying at around 50 pounds. You never know till they reach adulthood, and it's fun seeing just how they'll turn out :)