I don't have the measurements for the chalk cloth and the interfacing handy. I'll edit that in later.
I cut strips of a relatively stiff interfacing (that I already had on hand) 2.5" wide. I added the 5" length as well, to keep the rectangle consistent.
My cutting was sloppy at best. Sewing them on was an aesthetic nightmare. Nothing neat there! I used a leather needle (heavyweight) because I didn't want to break a ton of needles in the vinyl (still broke too many)!
Center the facing strips and the piece of vinyl by folding them in half and marking with a pin to find the center. Do not stick the pins in anywhere that's not going to be covered in fabric eventually.
I pinned the facing to the back of the cloth with a narrow overlap. The corners overlap and I trimmed them to make them more squared off.
Next I took a yard of 45” wide woven fabric and positioned it with the right side of the fabric and the right side of the chalk cloth facing together. A cut edge of the fabric is placed along one of the long ends of the chalk cloth.
Set it so that there will be enough on the one side to pull over to the front and tuck a hem on it. The cut edge should be lined up so that you can sew a secure seam (no frayed bits) onto the vinyl.
Straight stitch that seam from one edge of the vinyl to the other. Do not stitch the fabric to the facing..