How to get Canadian Visa for H1B restamping

[nicearyan]

Hi, I am on H1B status and recently change my employer.   I have recieved the approved petition and now  I need my visa stamping done in canada but i do not have a canadian visa to go to canada.  To get canadian visa, what reason shall i put in the application form.  I have not been able to get an appointment date from US consulate in canada, so if i put the reason as H1B restamping, will canadian embassy ask for an appointment letter as proof?  If i put the reason as visiting canada, will there be an issue since my visa is stamped for old employer and the petition is for the new employer?