Please clarify. Are you trying to use the Surface RT to remote desktop to the HP laptop or the other way around?
Assuming you are using the Surface as the controlling computer and the HP is the host.
- Check the version of windows on the HP laptop - it must be Pro, Enterprise, Business or Ultimate to accept RDP sessions. Standard Windows 8, 7 Home (and home premium) do not support hosting
- Make sure that remote desktop is enabled on the host computer (not remote assistance)
- Try disabling any firewall software on the host PC (windows firewall will block incoming connections unless an exception is made)
- Try connection using start-run mstsc and connecting to the IP address of the HP laptop (start - run cmd ipconfig)
This is all based on RDP on the same local network. If you are trying to get remote access over the internet then a 3rd party program or router configuration would be required. If its for non-commercial use then team viewer would be your best free alternative.