I found this website an invaluable resource:
www.felinecrf.org/which_foods.htm
I tried every single wet renal food on the market with Old Lady Cat and she made it quite clear she would rather die than eat them.
She loves a kibble though and so is settled on her renal kibble.
She also gets one Sheba Cat Soup a day to up her fluid intake as the website said it was relatively low in phosphorus + some cat milk (when she deigns to drink it). She loves the Cat Soup and would like to live on that alone, thank-you very much. She also doesn't eat lumps - we give her a tiny amount of Animonda Carny and think, what the hell, she likes it. When her bloods are worse she can have Ipakitine on it.
We also feed Thrive treats as she needs to put weight on.
The idea of the renal diet is it is low in phophorus and high in accessible protein - unfortunately it is also disgusting to most cats.
Starting out with an underweight cat, we have gone for a compromise position - she eats mainly renal food plus other stuff that is as good as possible from the non-renal menu as the most important thing is that she eats. Doing this she has managed to put some weight on and is a much happier cat.
When she really didn't eat as she was v poorly I did most of the tips from the website and it really got her eating - sitting beside her made a lot of difference, hand feeding, raising the bowl all actually worked.