Circuit to drive a Solid State Relay
20mA is the per-pin limit for an Arduino which means you could burn out the pin if you somehow exceeded the current draw even by a little.  Since you are driving an AC load I'd want some isolation in case the relay burned out.

The best thing is to use a transistor or optoisolator as the switch, that way your Arduino is protected.

I suggest using this circuit:
http://dlnmh9ip6v2uc.cloudfront.net/datasheets/Widgets/SSR-Board-v10.pdf

Circuit is from this Sparkfun product:
https://www.sparkfun.com/products/10684