Right hand side? I take it that you're standing infront of the engine, if so it's most likely the fuelpump that has developed a leak, the large topmost as well as small side gaskets are easily replaced. The gaskets / o-rings are inexpensive ~£2.50 for the large contoured top and a few cents for the o-rings.
Unfortunately if it's the lower contoured gasket the pump needs to be recalibrated or the engine wont start /run rough/rev like crazy.
Final worst case scenario would be the main o-ring on the output, high-pressure, side, it can be done but it involves taking half the pump apart.
yes as you stand in front of the engine. Just had another look, and the leak is coming from the pump area. do you have the part numbers for the gasket etc?