Chairman's letter for IMG

IMG YOG 2016. Applying to FAmily medicine and internal medicine I saw many IM programs requiring one of the LoRs from chairman of department of medicine. I currently have 2 US LOR(1FM 1IM) and 1 from my home country. Since I don't really know the department chair personally(Never worked with him), I have no idea how to fetch this. I read elsewhere saying Chairman letter doesn't matter for IMGs. Should I attempt applying to those programs requiring chairman letter without one?
Source: Student Doctor Network - Category: Universities & Medical Training Authors: Source Type: forums