That says, we cannot RDP to the virtual machine, but …. we can RDP to the host machine nei.
http://www.macrium.com/help/v5/How_to/ImgToVHD/Create_a_virtual_machine_using_ImgToVHD.htm
on this web it said:
Oracle provides two versions of VirtualBox, an open source edition with missing RDP and USB support, and a commercial version that is free for evaluation or personal use that includes those features.