There are several ways to use the RadSplitButton via the keyboard only:
Set its TabIndex property and use the Tab key to navigate to the desired button and then press the Enter key to invoke a click on the button.
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".
Once the SplitButton is focused, you can use the
Down Arrow to open and focus the button's ContextMenu. Then, you can leverage the ContextMenu's keyboard support to navigate, select and close the dropdown.