On my page, I took a piece of kraft cardstock approx. 5" x 7" as a photo mat and scored it diagonally. Instead of placing one side of the cardstock against the top edge of the scoring board, place one corner at the top of the scoring board, and line up the opposite corner along the length of the same score line. I flipped the cardstock around to line up the other corners and scored to make the diagonal scoring pattern. To add a little bit more texture, I used white thread and a machine zigzag stitch along a few of the scored lines. Here's a closeup of the photo mat.
And here's the finished layout, with the photo placed offcenter on the mat.
I hope you'll check out the projects @ Practical Scrappers and be inspired to get out your scoring board!