This is the d-i-y range. Mine's about 15 years old, but it looks like the Rubi Star40.
of pressure to snap but, for your average floor tile, you just bring the handle down with more of a hammer action. It's all about the score line being continuous and uniform (and in the singular). Too much pressure and the cutting wheel can't turn. It's a good idea to practice with some cheap tiles or offcuts to get a feel for the thing. After half an hour you can literally do it with your eyes closed