Chicken only isn't bad if the dog is ill. Chicken and overcooked rice isn't bad if the dog is ill. Neither is a good enough diet forever but is fine for a couple of weeks if you must.
You can use a blender to really mush up the stuff so the chicken cannot be picked out, that could work. You could mix in some egg and water and bake into a loaf, that might work. Make sure the rice is overcooked and mushy or it could just come out the other end undigested. Do use at least half chicken to half cooked rice which means for a 5 pound whole chicken you would add about 2 cups of raw rice. And if you think this is going to be going on for a while use 1/2 tsp of powdered egg shell per pound of meat so the diet at least has an appropriate amount of calcium. Toss in the egg as well if you aren't having eggs for breakfast!
That's a good start. Make sure you take the dog to the vet and get his health checked as well as to check for a microchip or tattoo. He may have parasites, worms, illness or bad teeth that are effecting his appetite or ability to eat kibble.
What kibble are you feeding him? If it's a good kibble, he should probably want to at least try it. Try adding a little water to the kibble to bring out the aroma and soften it a little. Eventually, lessen the amount of chicken and rice and increase the amount of kibble. You may need to employ a little tough love. A healthy dog won't starve himself for long. The longest one of mine has held out is three days. If you're going to keep him, a vet visit is in order, as mentioned above.