Add all ingredients to the slow cooker except for the broth and kale.Pour the broth into the slow cooker, and gently stir to combine.Cook on low setting for about 6 hours, or on high setting for about 3 ½ hours. As all slow cookers vary, cooking time may be different in your slow cooker compared to mine. Near the end of the cook time, check to see if the rice is done. Once the rice is tender, the soup has cooked long enough.Remove the bay leaf.Stir kale into soup. Serve.