Chalked Edge Effect
Tutorial - Chalked Edge Effect
Using Paint Shop Pro - Open new canvas 600 x 600 pixels 300 pixels per inch
Fill with your colour choice
On copy layer
Go to freehand selection tool - draw a narrow random selection quite close to the edge
all the way around your canvas to select the edge to be chalked.
(You could also Select modify and contract however much you want to)
Delete inner selection. (leaving edge on canvas) Select None.
Effects / Art Media Effects / Coloured Chalk - detail 20 - Opacity 20
Adjust Blur Gaussian Blur 13
Adjust add / remove noise - add noise - uniform - monochrome - 17%
On Chalk Layer Adjust /Sharpen and change layer property to Lighten.
(Optional - Apply texture to both layers)
I used Texture Canvas Coarse, size 150 depth 1 (smoothness, ambience, shininess 0)
Angle 315, Intensity 50, Elevation 30.
Merge Visible Layers and Save
Try this technique with other shapes.