It would probably be best to let the lizard go and if your chickens find it, they'll find it. If they don't, then they don't. Usually if I find frogs or anything else(other than bugs or snails), I release it and leave it to chance.
Lizards carry salmonella and as such handling them or having them walk on your food can pose a health hazard to humans. However, I don't know if chickens can pick up salmonella from eating a lizard. That said, I'm not sure how you could keep a chicken from eating one if it was able to catch one, but I'm not sure I would go out of my way to feed one to a chicken because of the possible salmonella infection it could cause.
my chickens eat lizards and frogs that they can catch when free ranging (only a few because they are fast) but I never catch any for them to eat.....I feed them worms and mealys that are raised for them to eat....and we need the frogs and lizards in the yard to eat the mosqitoes and such.