Take a look at these links
Kingsley are good presses, but are now antiques.
You will need to have some method of attaching your brass stamp to a block in the type holder. The double sided tape makes that easy. There is very little working space under the type holder, so would be difficult to place the stamp, press it down to heat it up, then remove it, place the stamp on your leather, then move the package back under the type holder, keeping everything perfectly in position.
When your stamp is properly attached to the block in the type holder, you let it warm up to the desired temperature, position your leather, pull down the lever pressing the stamp into the leather for a few seconds. The dwell time you need depends on the foil, leather, and amount of pressure you apply.