At 4 months your kitten can start eating soft kitten food, be careful about giving it any canned food as it may cause severe diarrhea and cause weight loss and sickness. If it still needs a little help gaining weif\ght give it some d\soy based infant formula, not milk base as it can cause sickness, and avoid giig cow milk as i could as\lso cause problems. Good Luck!Enjoy your new kitten!
At 4 months the kitten requires the protein and vitamins which are already available in the market in form of kitten can food. At this age they can have both dry and canned food.