Don’t let what you see in your choice of elements limit you. For example, this shape is the perfect mat for a square photo but you happen to need a rectangle.
However, if you stretch it out to a rectangle, the scallops are stretched out. This does not look right! There is a way to get around it with this shape and several others (but obviously not all of them).
1. Insert, Shape from Content Section, From art kit, Decorative Cardstock Digital Shapes, Shape 14.
2. Duplicate the shape and change the color.
3. Zoom in and line up the scallops while creating the rectangle size needed.
4. Flatten the two elements together and fill with color, paper or a photo.
Now, THAT was easy!