When you use Hi-res production to produce a traditional matted layout, ProSelect will create separate print file for each image in the layout. These images will be sized based on the shape of the opening in the template and fitted within the selected Print Paper Size. (See the ProSelect Reference Manual for more information on how Layouts are sized). 

When you apply a style to the layout, you will notice that the images will get smaller in each opening because they are shrunk to accomodate the width of the border setup in the style. By default, this allowance for the width of the border is automatically removed when you run production on a traditional matted layout, so the images will be sized to fit the opening sizes without the border.

However, you can change this behaviour by changing the Preferences -> Hi-Res Production -> Style Options -> Traditional Matted Prints. As mentioned above, this is normally set to Ignore Applied Styles. If you select Add Borders or Add Borders to First Bevel, then the Style will be applied to the edges of each print that is produced.

For example, you can apply a style with a Keyline, Space and a Bevel to a layout to show your clients what an overall traditionally matted print with a indented space and keyline will look like, then (with the setting Add Borders to First Bevel) automatically produce the correctly sized print with the keyline and surrounding space ready to mount. See the ProSelect Reference manual (page 123 in the version 4.0.8 manual) for an example of this.