The last Standing Palm posture is the main posture for Baguazhang practice, and you can add it as a fifth posture for your standing practice.
Assume the left Universal Post Posture on the edge of the circle facing in the counterclockwise direction. Drop the heel of the left foot and place your hands into the Trinity Posture positions. Then turn your upper body so the forefinger of the left hand aligns with the center of the circle.
The right hand will move naturally to the left as you turn. Bend the elbow of the right arm and stand the right hand up so that the fingers are under the left elbow.