Click on the crop tool and enter the height, width, and resolution you want your photos to be.

On all four photos, click and drag a crop outline around the area of the photo that you want to retain. Click on the check mark in the Options Bar to accept the crop.

Create a new document (File > New). Make sure that it matches the resolution of your photos and that it’s large enough to contain all four photos. I used a standard letter size for mine. Click on the Move tool (top, right tool), and move each of your photos onto your new document.

Click on the eye of the background layer to make it invisible.

Then choose Merge visible from the flyout menu at the top of the Layers Palette. Turn the visibility of your background layer on again by clicking where the eye should be.

Make sure your photo layer is still selected in the Layers palette. If it isn’t, click on it to select it. Click on the Rectangular Marquee tool (top, left tool) and click and drag a rectangle close to the edge of your photo as shown.

Choose Select > Feather from the Menu Bar and enter a value of around 20 to 40 pixels depending on the size of your photos.

Press your delete or backspace key and then choose Select > Deselect to get rid of the selection outline. This is how your photomerge should look.

If you don’t get the look you want, press the step backward arrow in the Options Bar until you get back to your rectangular selection, and try a larger or smaller feathering value. You want to choose just the right amount of feathering to make the edges soft and see through, but you still should be able to see the straight edges of the rectangle.