Any commerical dog food which you can buy from supermarket, generally are bad in ingredients.
Personally quite like this web-site:
http://www.dogfoodadvisor.com/dog-food-reviews
However, these brands are mostly base on American brands and I am not sure would Hong Kong have these.
Royal Canin, is an average dog food. It is not price for value I would say. I have no idea what is your dog ( bitch) breed is and age, not easy to make a recommandation.
My two huskies are on Orijien puppy large breed, I assume it is quite a tasty dry dog food since one of my picky dog -eater still happy to have this over a year. It might not suitable for your dog as this puppy large breed is quite high in animal base protein and might make your dog gain weight easily.
About the fussy eater, do remember to offer the food for 15-20 minutes, and remove if she isnt eat after the time. repeat as a daily routine, she will learnt the lesson. ( only one type, don't make A meal for monday, B meal for tuesday and C meal for wednesday, it just make the dog more fussy to pick to eat)
Regarding the pigment on the skin.. if you are corncern, you should take she to see the vet.