There are Scots, Scotsmen and ”Caledonians” (a Latin term). There is no such thing as a Scotchman or a Scotch man! “Scotch” refers to a type of whiskey, or some item of food that is distinctively Scottish, such as Scotch eggs or Scotch broth. It does not refer to people. The citizenry of Scotland are best referred to as Scots, which is also a correct way to identify an inanimate object — “That’s the Scots flag,” or “He’s wearing a good Scots kilt.” “Scottish” works well as an adjective.