Hello alex,
may I suggest the following technique in Xara:
Choose a ragged brush and create a rectangle.
Now choose Combine lines to shape. If the fill dissappears you can combin another rectangle with your shape.
See my attachment
Now you can either use it as a clipping mask for your photo or just fill it with your picture.
I know that it doesn't give you the torn page effect exactly but it's a workaround
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