I'm not quite sure what you want to achieve as the example is a poster. However, Adams dry-mounted his prints with an open area between the edge of the print and the interior edge of the window mat. That is usually called "float" mounting. At the AIPAD show, I even saw some prints that were mounted that way but with corners rather than dry-mount tissue.
If you search this site for "dry mounting" you'll likely find some lengthy discussions of various techniques.