If you feel that the default on-screen keyboard on the Surface RT isn't sufficient, you can enable what I would say is the "pro" keyboard via the settings.
- Drag in from the right hand side to show the charms and click Settings.
- On the bottom of the settings window, click "Change PC Settings" to show the Windows 8-style control panel.
- Under General... Touch Keyboard... turn on the option called "Make the standard keyboard layout available".
Now when you're displaying the onscreen keyboard, there will be a fifth option available which is a more "standard" Windows keyboard including up arrow, down arrow, and the option for F1-F12 if you hit the Fn key first. I still haven't found a way to show Insert/Delete/Home/Page Up/Page Down other than with the physical keyboard.