1.- First make a new layer on top of all the sig layers that you made and name it "Border" or just leave it as is.
2.- Second go to "Select" and click on "All" your layer should be all selected now.
3.- Now go to "Edit" then "Stroke" and put a 5 pix black color and click on "OK".
Next go to "Edit" then "Stroke" again and now input 3 pix instead of 5
white color and click on ok.
now you ar almost done go to "EDIT" then "Stroke" again and input a 1 pix black color and clik on ok.
now deselect the canvas by going to "Select" then Deselect and your done.
if you decide to put a different color in the 5 pix and 1 pix then do so depending on the color of the sig that you will be making.