pathfinder – How does the monk's feat work?

The magnificent fist feat says:

You must declare that you are using this exploit before making your
Attack roll (well, a failed attack roll ruins the attempt). Stunning
The fist forces an enemy damaged by your attack with his bare hands to form a Fortitude
save roll (DC 10 + 1/2 your character level + your Wis modifier),
in addition to inflict damage normally. A defender who fails
The save roll is knocked out for 1 round (until the day before your next match).
tower). A stunned character drops everything that is held, can not take actions,
loses all dexterity bonus to AC and takes a penalty of -2 to AC. You can
attempt a breathtaking attack once a day all four levels
reached (but see special), and no more than once per turn.
Built, oozes, plants, undead, incorporeal creatures and
Creatures immune to critical hits can not be knocked out.

The Crushing Blow feat declares:

You can make a superb fist attempt as a complete action. Yes
successful, instead of stun your target, you reduce his
An amount equivalent to your wisdom modifier for 1 minute. This
the penalty does not stack with other penalties applied due to the crash

I do not know how it all works. Crushing Blow specifies a full action, so I thought it was just the Fort Save for the enemy, and then you would get the effect, or you would not do it. Since there is no normal attack, this can not cause failure either, but you can not do damage either.

During the game, I discovered that others were not in agreement. Their interpretation was that I always had to make a normal attack, and then, if I tried to hit, the Crushing Blow – a bit like a different effect option for Stunning Fist that prevents moving actions?

So, how can I use this exploit? In itself or as part of a Standard Attack hit?