Joey wrote:

Les,

Do you want to use what the Pros use? It's call a Pumice Stick. Lowe's
did sell it and you'll find it at a specialty cleaning supply warehouse.
You wet the end and run it around the rust line and it's gone.

Pumice is an abrasive. Do not use abrasives in the bowl. You will
regret it. It will make bowl more susceptible to staining in the
future, and harder to clean next time.