It is on the ride side just above the USB port. You can find the adapter there at the Microsoft Store as well.
The micro-SD port can also be a challenge to find as well. You open the kickstand and is located on the lower left side when facing the back of it.
I never hooked mine up to test it. I have a mini-notebook that has a real HDMI port and a real SD card slot (plus has a VGA port as well) that I am starting to use instead. The unreliability of WiFi has put my RT at risk of going back into its box and be stored in a closet forever.