Royal Canin Veterinary Diet Dental Dry Cat Food as a cat treat or raw meat diet topping?

Hello. my cats are on raw meat diet for almost 3 years now and they're doing good but, in order to have them to eat their meals, I had to start adding some high quality canned food mixed with raw, just enough to entice their appetite. I am also trying to find a good dry food (still, JUST as a topping to sprinkle on top of wet food) that won't cause my cats diarrhea or chin acne and with kibble good enough so they will actually have to chew on them rather than swallow it; the only one I've found so far is Royal Canin Dental dry cat food and, although it is not the best helthy choice outhere, It is the only one that doesn't bother my cats and somehow I was hoping it would help to keep their teeth cleaner?! My 11years old male already have his teeth cleaned twice and he developes tartar on his back teeth so quick and it seems like me brushing every night is not helping much... I am aware that kibbles are bad and don't "clean" the cat's teeth but I am desperate to try that too; again, I will probably give a total of MAX 4 pieces at day.....will that be that bad for them? P.S.: I tried raw bones..lthey don't care for it 8-(
Did anybody try Royal Canin Veterinary Diet Dental Dry Cat Food and experience any positive experience on their cat's dental health?

Also, on my raw meat recipe I always use turkey thighs and some chicken thighs and 2-3 times at week I add just a bit of ground rabbit: if I want to introduce a different source of protein, what kind of beef part should I use?

Thanks in advance for any help.

I am not familiar with any of the raw food options or choices there and the Raw and Home Cooked Forum is where the discussions and information are held for that type of information.  I know that many who live with cats prone to plaque and tartar build up feel the raw feeding helps.    However, in relation to the dry food question you started with here, my thoughts are that the prescription and other marketed dental dry foods need to form the majority of a cat's diet for them to benefit from the dental cleaning effect - I feel the Hills Prescription TD and as a result feed only tiny quantities of freeze dried protein snacks as an alternative  (my cat is not interested in wet food at all, probably associating it with when he felt very sick and in pain).  

You don't mention the type of tooth paste you are using but hopefully it is one of the enzyme pastes, and if possible use this in a small quantity daily and brushing particularly in the area of the mouth you feel is affected.  If the gums are inflamed I wouldn't use a hard brush though and stick to something soft life a cotton wool bud, or finger and gauze.