You can use Jorudan but I prefer Hyperdia. If using a Rail Pass, be sure to uncheck "Nozomi/Mizuho/Hyabusa" in "more options" as those trains are not available for Rail Pass users.

http://www.hyperdia.com/en/

For the round-trip Tokyo-Kyoto-Tokyo PLUS at least a one-way to/from NRT, the 7-day ordinary Rail Pass will more than pay for itself. If only using the train for the round-trip without any other rail segments, you are better off just paying as you go without the Rail Pass.

Of course, a Rail Pass can also be used for Kyoto-Nara, Kyoto-Osaka, Kyoto-Himeji or Kyoto-Hiroshima in addition to the other segments.