I have a form created in .OFT format.
i want to automatically add a button to the main Outlook window that will
open this form.

I can do it manually - be creating a button with "Edit hyperlink" menu
I also found this script:

Sub MakeItem()
Set newItem = Application.CreateItemFromTemplate("c:\your path\open test.oft")
newItem.Display
Set newItem = Nothing
End Sub