H1回國休假，應該讓公司出什麽樣的supporting letter幫助簽證？謝謝

Employment letter is optional. You may ask your employer to state your position & emplyment period in the letter. But when I applied H1B visa last year in US Consulate General @ SH, the immigration offer only asked for my I797, passport and 2 application forms (even not asked for other back-up docs). Good luck!