Drill a row vertically of No 6mm holes one above the other to make (with use of chisel) a narrow slot for the thumb bar to go through the door, about 90mm back from the shutting edge.
Fix the handle onto door using one screw only in top and bottom, fix so that the thumb bar going through door is level.
Position latch bar on other side so that the lower edge of bar rests on top of thumb bar and hangs over the edge of door by about 30mm. Put screw in central hole leaving loose enough for bar to move up and drop down freely. (Check that when pressing down with thumb on handle side that thumb bar rises to lift latch bar).
Mark lines across face of frame to show position of frame keep. When bar is horizontal drill a guide hole into frame (3mm dia) just under this line to a depth of 25mm, about 15mm from inside edge of frame. With the door closed and latch bar going across frame the point of keep should enter hole, if you tap keep into frame stopping before it pinches latch bar.
If you push down on thumb latch or lift hooked end of thumb bar the latch bar should rise up out of keep.
We supply a staple pin which is driven through door and clenched over, or a simple screw in staple if you prefer. It needs to be fitted about 25mm back from edge of door over latch to keep bar against door.
If all parts work door opens and closes put remaining screws into handle.