Here is a good video showing a ridge cut for venting a roof vertically. Don’t forget that on a real fire, you need to wear SCBA and it is still optimum to have a roof ladder to help to operate off. In addition, care must be made to ensure that the roof is stable enough to cut the ridge without total collpase of the roof.
This is typically used on steep pitched roofs that are difficult to vent off of the roof ladder. Be careful out there.