Rehd,

I double check the notches in the forms in Putz's book against yours. I think you'll see that Putz's notch on the forward frame you show in your picture is cut so the inside edge of the cut is perfectly vertical, and only the outside edge is perpendicular to the edge of the form. For your notches you have both of the sides of the notch perpendicular to the edge of the form. Without the relief from the wider notch you may have a difficult time lifting the frame off of the forms.

Sure you can twist the wood strip into the notch you have, but you'll want to lift the entire frame striaght up to remove it from the building forms. Chisel that notch wider while you have the chance.

PGJ