It only takes a little planning to get good results. I think it is easier to understand how to measure your starting piece of paper if you know how the process works. Therefore, here is how I went about creating the frame. Let's start with a diagram of how we are going to punch our paper.
As you can see from this picture, we never actually punch our border completely down one side of the paper. First we measure how deep the design is that is punched from the paper. I took a piece of scrap paper and punched a design on it. I then measured the depth of my design (see below).
My design was 1/2 inch deep. Our first punch on our square is going to start 1/2 inch from the edge of the paper. I take my piece of paper and mark in pencil a line 1/2 inch in from the side, be sure to make your line long enough to be seen in your punch.
Now hold your punch upside down so that you can view the bottom of the punch. Slide your paper into the punch and line the pencil line you made up with the side of your pattern. Your pencil line should be visible where where you see the blue arrow below. Now punch one shape while holding the punch upside down.
Your punched shape should look something like the picture below.
Turn your paper over and continue punching the rest of this side of your square paper. Make sure you punched all the way to the edge. Your paper should look something like the picture below.
We have one side punched but now we have to turn the corner. You are going to turn your punch upside down again. This time we are going to make sure when we slide our paper into the punch that our pretty punched edge is just outside the visible window of the punched pattern. In the picture you can't see any of the decorative design I punched on the previous edge.
After you punch your corner you may have a stray piece of paper that you want to remove. With the particular punch I choose I had this little tiny piece I didn't want in my finished frame (see the blue arrow below), so I just clipped it off with my scissors.
Continue around your square (or rectangle) keeping your design on each corner just outside your punch pattern. You should have an easy time getting all the way around your shape.
To turn the shape with your punched edge into a frame, just decide on the width our your frame, mark a square and cut out the center of your paper using a rotary cutter, scissors or knife cutting tool. My frame was a little over 1/2 in deep (including the design edge).
I want to give you a helpful hint on how to measure your paper if you are using a punch that has an even pattern that repeats. Your frame will have corners that look the same when you size your paper to fit the size of your punch. Now that you have seen how the process works it is just a matter of doing the math to figure out the starting size of your square. One side of your paper needs to be the length that is equal to one depth of your punch (in my case 1/2 inch) plus the length of the number of punches you want to make (in my case 4 punches). So the square that I stared with was 1/2 inch plus (4 punches x 2 inches long) 8 inches for a total of an 8.5 inches square.
Hope you will give this a try and add a pretty punched frame to your next layout!