My puppy also eating royal canin (mini junior) since he was 2months until now 6months already.
There are 2 types of royal canin food: veterinary (only sold by vet clinics) and non-veterinary (sold by pet shops).
Veterinary pack is better because it has thyroxine which is good for dog's skin and coat according to the vet in the clinic. I bought at RM68 for 4.5kg at Maju Animal Clinic in Melaka. If am not mistaken, the 2.5kg is sold at RM48. Usually i buy the 4.5kg one because it is cheaper.