German Shorthaired Pointer Q&A
The ridge is present at birth and will not come in later. Some Ridgbacks are born ridgeless.
Remember, your puppy is only 3 months old and hasn't matured yet so give it some time.
Regarding the maturity answer. A ridge will never grow if the dog was not born with one. Maturity has nothing to do with the presence of the ridge. Pure bred ridgebacks can be born without a ridge. If one needs information/education, please refer to www.rrcus.org This is the parent club for the Rhodesian Ridgeback.
I was told Brazilian Rodesian Ridgebacks-actually don't have ridges-a vet tech told me this.