Defrost Chicken. Trim off fat (and cut in bite size pieces if desired).
Place Chicken in casserole dish and cover with sliced swiss cheese.
Mix together 2 cans (or one large can) cream of chicken soup, 1/4 cup water and 1/2 cup sour cream. Pour mixture over chicken and cheese.
Melt one cube of butter and mix with one package crushed ritz crackers. Put on top of chicken.
Bake uncovered at 275 for 2-2.5 hours or covered at 350 for 1 hour. Serve over rice.