Warm the sauerkraut and turkey, separately, in a microwave-safe bowls for 30-seconds; set aside. Spread butter generously on one side of each slice of rye bread, then spread the thousand island dressing on the other side. Divide the sauerkraut, turkey, and Swiss cheese on two slice of bread with the butter-side down. Stack the remaining two slices of bread with the butter-side up on top.
Heat a large skillet over medium-low heat. Arrange the sandwiches on the skillet and grill until lightly browned and the cheese is melted, about 3 minutes on each side.
