Align Vertices in Skewed Plane

I’d asked a similar question a while back, but that was for something different, but how would one align vertices in a plane after using Knife Project tool? To be specific, this is in a non-perpendicular plane, not aligned to any axis. Suppose a random rotation, such as 37 degrees.

Knife Project cuts out a shape in the rotated plane, but the vertices of the cutout are ever-so-slightly off the original plane. How would one align these back into the plane, to form a perfectly-flat surface, while retaining the shape of the cut?

Will hopefully have have pictures up by tomorrow.

Regards, Ron

Make a new transform orientation from the face and make sure to check use after creation. Then scale to zero along the z axis of the orientation.

Use LoopTools - Flatten on edgeloop?