As with most of Photoshop there are various ways in accomplishing the goal. In this case the goal is to outline an image with a circle then crop the image to that circle.
Here is one way.
Add a new layer to your image.
Select the elipse tool
Set the Elipse Options to circle.
Draw your circle. Placement doesn't matter at this point.
Set the fill properties to zero percent.
Set the blending options.
Set stroke to position to inside. Set desired color and width.
Move circle into position.
Put the mouse pointer on the color square for the circle, hold the Crtl key and click that square.
That selects the circle.
Inverse the selection.
Click on the layer with the image to be cropped. Press the Delete key.
Tutor Tanith
