Have a look in a local pet supply store for food from By Natures Organic, Innova Evo 95%, Wellness, Taste of the Wild, Evangers they may be a bit more expensive but are healthier options than what he was previously eating. The k/d is super low in phosphorus, but also fat & protein making the food not that appetitizing. A higher quality meat sourced food will go a long way in improving his health, it won't cure the CRF or HD but will provide for a better energy base, muscle mass and immune system.
What you want in a kidney friendly dog food is moderate to high fat, moderate protein, low phosphorus, not low everything such as the kd - there is very little actual meat protein in the kd. When you have a higher quality protein source the phos levels are lower than a poor quality source.
Stabbing yourself does tend to happen on occasion when preparing injections
. Sounds like he tolerated the treatment quite well