Thank you all for your comments. I do dry mount my prints (on acid-free foam board), and overlap the print border with the mat. It is the print border that shows and not the backing board. Perhaps with glossy prints I can change that practice.
What is the importance of having the signature show on the front?
"Often moments come looking for us". - Robert Frank
"Make good art!" - Neil Gaiman
"...the heart and mind are the true lens of the camera". - Yousuf Karsh