the residency at HMC is Arab Board and is recognised in all the GCC countries.. Yes you can work in Saudi Arabia wit it ,you can work in any of the GCC countries with it. keep track of the application process and deadlines on the "medical education section" of their website

http://www.hmc.org.qa/hmcnewsite/

Follow their residents group on facebook and you will get answers to most of your questions.

Best of Luck.