I'd suggest you find them via Social Media.
A great & experienced social media manager will be active on various platforms and will know where to find what they're looking for. As you can see, Boris already introduced himself & his interesting profile.
If you get to know the person & get references from the people they've previously worked with, then I'm sure you'll find somebody that's trustworthy and can do a great job for your company.
The person I plan to hire soon isn't offshore, but a few hours away from me, which equates to the same thing most of the time (coordination via Skype, tasks/KPIs via eMail/CRM). The distance doesn't concern me.