Modified from a recipe I found on AllRecipes.com - removed the potatoes to make it more Atkins compliant, changed the sausage to turkey kielbasa for low-fat.
Place half the sauerkraut in a slow cooker, and top with the sausage. Cover with the remaining sauerkraut, apples, and onion. Pour chicken broth over all, and sprinkle with caraway seeds.
Cover, and cook on high 3-4 hours or low 6-8 hours.
Place each serving in a broiler-safe individual bowl or casserole, sprinkle with Swiss cheese and place under broiler for 1-2 minutes until cheese turns bubbly and brown.