Hi Denise, when I first started printing platinum I used a printing frame with the spring clips and just couldn't get good contact every where. I was stuffing sheets of foam or mat board or anything I could to force the film to stay in tight contact and just had bad luck. I switched to using 1/4" plate glass on top and bottom and clamps all along both sides and got much tighter contact with film and paper. I keep the glass sandwich close to the paper size. I really don't think there is a better way except with the vacuum.
Dennis