Sidebar for a single page confusion

I'd like to to show one of the optional sidebar widgets (Optional Sidebar One for example) on a particular page. The default layout for the site is "No Sidebar (Full Width)". In the page layout options I'm not sure what to choose: "Default" isn't right because that doesn't show a sidebar, the two "Primary Sidebar" options aren't right because I don't want the Primary Sidebar and the other three options are "No Sidebar *". What do I do? I've tried all the combinations I can think of but the sidebar never shows. Thanks, Alex