Call the renewal number and follow directions.
If you have your library card available, you can use it to log in. (Link is in the top right corner.) Once you've logged in, click "my SFPL", it will show you links for "checked out", click that to see the full list with due dates. Check the box next to the items you want to renew, then click the button at the top of the page for "renew selected".
Agrees with @Patrick & @Cherry
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