How would I cite multiple authors from an online forum? How would I cite two authors from this online forum (http://www.thenation.com/article/one-thing-do-about-food-forum)?
The forum is edited by Alice Waters and my quotes come from Wendell Berry and Peter Singer.
In my paper, I include the in-text citation (example below)

Singer mentions that &quot;Etc etc etc&quot; (qtd. in Waters, ed.)

Originally, the citation in my bibliography was ...

&quot;One Thing to Do About Food: A Forum.&quot; The Nation. Ed. Alice Waters. N.p., 11 Sept. 2006. Web. 01 Oct. 2014.

but is that actually correct? Do I have to instead reference them like ...

Singer, P. &quot;One Thing to Do About Food: A Forum.&quot; The Nation. Ed. Alice Waters. N.p., 11 Sept. 2006. Web. 01 Oct. 2014.
Berry, W. &quot;One Thing to Do About Food: A Forum.&quot; The Nation. Ed. Alice Waters. N.p., 11 Sept. 2006. Web. 01 Oct. 2014.

I'm not too sure how I would go about in this so any help would be appreciated. Thanks!
Starting with the principle that the goal of a citation is to make it as simple as possible for somebody to find the particular reference, I can see two ways to approach this publication:


Treat it like a journal special issue or chapters in a book, where there are multiple articles bundled together under one editorial title.
Treat it like a single multi-author article.


In this particular case that you have linked, it seems that none of the contributors have titles for their individual sections.  That means that you can't readily separate out the individual contributions.  I would thus recommend citing it as:


  Alice Waters, Jim Hightower, Eric Schlosser, [etc], "One Thing to Do About Food: A Forum." The Nation, 11 Sept. 2006. Web. 01 Oct. 2014.


Then you simply to who you are quoting in the main text like you are already doing.
If they had individual article subtitles, you could do:


  Singer, P, "Singer's Article" in "One Thing to Do About Food: A Forum." ed. by Alice Waters, The Nation. 11 Sept. 2006. Web. 01 Oct. 2014.


Without the secondary titles, though, listing Alice Waters as editor makes it sound like she's the editor of The Nation not the forum.

[Note: I think my style may be slightly off from your required format - the key point is the person/title pairings]