Sometimes the built-in "Outline" just isn't what you're looking for. You can only make it to a 5 point thickness and the edges are curved. What if you want a thicker white edge with square corners...just like the white edges you see around old photos? For that, you'll want to use the Vignette feature.
In ProShow Producer 5, you'll find the Vignette feature by clicking on one of the images in your Layers List, then go into the Adjustments Tab at the top. You'll find the Vignette option under the Editing Tools in the bottom right hand corner.
If you simply check the box next to Vignette, you'll get a soft, black, rounded corner Vignette around your image. In order to make changes to this setting, click on the button to the right of the check box that says "Vignette".
The default settings are a Rounded Rectangle Shape, Solid Black Color and a Vignette size of 10. Let's change these settings so that we get a solid White border instead.
Click on the Color Swatch next to the Solid Color Radio Button and a Color Wheel will appear. Drag the little Circle that is inside the Triangle all the way to the top to change the color to White. Click "Set Color" to accept your new color.
Now, click on the check box next to Solid Borders and that soft fade into the picture turns into a Solid Border. Now, it may look like a perfect rectangle at this point, but it's not. If you look closely, the corners are not pointed, but round:
If you also click on the Check Box next to Fill Corners, you'll get a perfect rectangle border around your photo.
To adjust the size of your border, change the Vignette Size to fit your needs!