There are several ways to use the RadSwitch via the keyboard only:
Set its TabIndex property and use the Tab key to navigate to the desired switch and then press the Enter key to invoke a click on the switch.
Set its AccessKey property. This allows you to use the browser's shortcut combination to invoke the click ("Alt + AccessKey" in IE and Chrome, "Shift + Alt + AccessKey" for Firefox, "Shift + Esc + AccessKey" for Opera).
Note: By default, tab-access is disabled in Safari. To enable it, check "Preferences > Advanced > Press tab to highlight each item on a page".