I was wondering how should I cite my SFN poster for my thesis proposal?
Posters and presentations are generally cited as 'Abstracts' with the standard information being presented as well as the conference title, place and full date of the presentation according to your bibliography style:
Clinton HR, Bush GW, Cheney D, Obama B. Effects of Adam and Eve on the diversity of Archaebacteria species. Abstract #1. Puerto Williams, Republic of Chile, Dec. 12, 2012.
In some cases Abstracts from meetings are published in Journals, often as a supplement. In these cases, one simply uses the standard journal style to reference the work. Often the volume number will be replaced by 'Supplement number" and pages will be replaced by the 'abstract number'