While Microsoft does sell video adapters adapter for the Surface RT they may not be necessary. I’m using a $6 cable to mirror the screen to my TV. I could have gone with a $3 cable if I wanted a shorter one.
The Surface has a standard micro-HDMI port for video out so any micro-HDMI to standard HDMI cable should work. I’m using this one when I need to reach from my couch to my TV and this shorter one for my PC monitor. Their combined price is ¼ that of the adapter.
By default the display will be mirrored but you can go into display settings and make the usual windows display setting choices – use one or the other monitor or extend the desktop. I was not able to get the Start screen or Metro apps to display only on the second screen when extending the desktop. I had no problem running desktop apps on my TV while Metro apps ran on my Surface RT.
In addition, sound was not transferred to the TV. If all you need is basic video then a $3 cable should cover it.
Press WINKEY + P to select the second screen configuration.
by Ray Newbery aka @osquest