I would like to know if silver jewellery's electroplated with Ruthenium might cause skin allergies in people.

Answer 1

Not likely. Ruthenium is more inert to skin sensitivity than some other fillers, like nickel or copper, but anything is possible.
If you find that you are allergic to the jewelry, then you can either paint it with clear nail polish (the cheap way) or protect it the right way with a jewelry coating.
http://www.aaajewelry.com/Allergy%20Help.html

Answer 2

Metal allergies are quite common with rashes