Preheat oven to 350. Position a rack in the middle of the oven. In a mixing bowl, combine chicken, bread crumbs, 1/3 cup ketchup, onions, egg, salt, and black pepper. Mix well. Transfer meat mixture to an 8"x 4" loaf pan, mounding it slightly; smooth the top with the back of a spoon. Bake loaf for one hour, or until loaf reaches 185 on a meat thermometer. Spread remaining ketchup over top and bake for another ten minutes. Let the loaf rest on a rack for ten minutes before slicing.