I am having the same problem. I just installed x8 for Mac. I followed the video instructions posted above, but this does not help.
I choose File >> Import - and then I select my .ris file. When I click the Import button, I do not get the Import File box that has the Import Options dropdown menu. I just get nothing.
Here is a screencast I recorded showing my process. drive.google.com/open?id=0BzVCZ1RNCcywTDdpOUhYZWlZZWc
Any help would be greatly appreciated!