Seeking Help for Dog With Chronic Kidney Disease

Hello,

Looking for some advice my 8 year old dog, who is now 33 kilos, Retriever Labrador, now has chronic kidney disease. I see apple cider vinegar is suggested but exactly how much? Should it be diluted in water and how much water. Does it need to be a special type? Is there anything else natural she should be taking that will help her recovery? She is on a prescriptive diet of Hills food for kidneys and medication prescribed by the Vet.

Many thanks in advance.