Hiya,
I'm new to Freelancer so please don't let my lack of ratings put you off, but please allow me to explain what I have to offer.
I am a fairly seasoned social media manager, and am currently a content writer for several SME's in the UK. I work across Twitter, LinkedIn, Facebook Pages (not Ads), Instagram, G+, and Tumblr, but not Pinterest as Pinterest doesn't allow their service to be used via the API of the social media platform I'm currently using.
Given that you don't have a wordpress plugin, we might not be able to set up an autoposter rss feed, however given that I use a SMM tool I'll be able to post these manually across all your social media profiles without any effort.
How often do you post? Also, do you have posts scheduled, or do you create each post one-by-one and post them manually? I'm asking because if you have a ready csv or excel file I can schedule these to go out on your sm profiles so that they coincide with your posts on your website. I can also provide a weekly report (PDF) for you to keep track of activity in detail.
Be sure to let me know if you have any questions, and we'll take it from there. We can also set up the milestones how you'd like.
Hope to hear from you soon!
C