Spray slow cooker with cooking spray. Lay chicken in bottom of cooker. Season with salt and pepper. Mix soup with 1/4 c. water. Pour over chicken. It will be a thick mixture. Mix stuffing mix with 1 c. water. Mixture will be crumbly. Spread over soup. Slice margarine and lay over stuffing. Put lid on slow cooker and cook 4-5 hours on low.