Marking out the strike plate
With the new lock fitted, close the door against the frame so that the lock bolt (and the latch) touch it.
Mark the top and bottom of these on the frame and open the door again.
Transfer these lines horizontally on the frame rebate.
As with a simple mortice latch, measure the distance from the closing edge of the door to the far edge of the latch.
Mark this distance from the door stop on the frame rebate.
Hold the strike plate in position on the frame so that the far edge of the cut out lines up with the mark just made and the horizontal lines match up with the top and bottom of the cutout.
Recessing and fitting the strike plate
Mark around the strike plate and recess the frame to suit.
Check that it fits flush in the recess before drilling pilot holes for the screws, and fixing in place. If necessary, counterbore the pilot holes to accommodate the screw housings on the back of the plate.
Check the operation of the lock when the door closes to ensure all items are lined up properly.
Slight adjustment in any direction may be made by slackening the strike plate screws and moving the plate. Holding it firmly in its revised position, re-fasten the screws.