Preheat a skillet over medium heat.
Butter one side of each slice of rye bread.
Spread dressing on the unbuttered side of each slice.
Layer corned beef evenly on one slice.
Add sauerkraut on top of the corned beef.
Place Swiss cheese over the sauerkraut.
Top with the second slice of bread, dressing side down.
Place the sandwich in the skillet, buttered side down.
Grill for about 4-5 minutes until golden brown.
Carefully flip the sandwich and grill the other side for another 4-5 minutes.