The Montrose is normally worn with a white (cream, ivory etc.) lace jabot or a cravat which can be plain or trimmed with lace and generally worn outside the doublet (i.e. not tucked in). I have also seen the doublet worn open at the top with a black bow tie.
It's coming yet for a' that,
That Man to Man, the world o'er,
Shall brothers be for a' that. - RB