Yes, the entire jar of prepared horseradish is spread on top of the roast. The flavor of the horseradish becomes very subtle during the long, slow cooking. It will give your pot roast a wonderful "secret" flavor.
The great thing about serving a pot roast is that everything—meat and vegetables—is in one pan. Complete this easy meal with a good old-fashioned dessert, such as warm apple crisp, bread pudding or cherry cobbler.