Usually, the easiest way to get a dropdown/vertical menu is if your RapidWeaver template comes with one. But now there is an alternative.
Menu Stacks provide Dropdown and Vertical menus that you can place on your page, whether or not your theme comes with one.
With Menu Stacks, you can control what you want to show in your menus. You can create menus that are different in structure from your site. You can use these on any themes.