Heat the broth and rice in a large saucepan to boiling. Reduce heat to simmering; cover and cook 15 minutes or until the rice is cooked. Add the chicken. Remove the soup from heat and cover. Whisk the eggs and lemon juice in a medium bowl until frothy. Remove about 1 cup hot broth from the soup and slowly add it to the eggs, whisking continually. Slowly stir the warmed eggs into the soup. Ladle into bowls and serve immediately with a slice of lemon.