How to Create a Root Phi Rectangle
One of the most popular rectangles among portrait painters is the root Phi. To create a root Phi rectangle, swing a line up from the bottom right-hand corner of a Phi rectangle (1.618) to the top. Where the arc meets the horizontal edge frame of the Phi rectangle, drop a vertical line down. See diagram below.
Painting above by Dot Bunn designed using a root Phi rectangle.
Painting above by Dot Bunn designed in overlapped root Phi rectangles.
Photograph above by Stephen Shore designed in a root Phi rectangle.