Add some support for using RefTeX citation management in pandoc .md files. See here:

http://stackoverflow.com/questions/13607156/autocomplete-pandoc-style-citations-from-a-bibtex-file-in-emacs

Note that either your default bib file must have pandoc-compatible keys (i.e., no underscores in the keyname field) or you'll have to tell RefTeX where to find the particular bibfile for your document. The easiest way to do this is to put a comment in your .md file's YAML block, one that contains a string RefTeX can understand. Like this:

---
title: Article Title
author: Kieran Healy
date: February 2014
bibliography: <!-- \bibliography{/Users/kjhealy/Documents/bibs/socbib-pandoc.bib} So that RefTeX knows about the bibliography -->
abstract: Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enimad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.
...