I always use a tapestry frame to support the canvas while I am stitching. A frame keeps the canvas taut and stops it from going out of shape and losing its structure.
I use two types of frames. For short pieces I use Siesta interlocking stretcher bar frames. For longer pieces I use a 15” x 12” / 38 x 30 cm Elbesee No Sew Easy Clip Hand Rotating Frame. Rotating stitched frames can also be used. Make sure the size of your frame is suitable for the size of the canvas. Advice on which frame to use for each design is included on each purchased pattern PDF.
There are a few different brands of roller frames on the market with a variety of methods of attaching the canvas to the frame. The most traditional is the stitched type but the more modern clip frames are quicker to set up once you get the hang of them.
Interlocking bar frames are available from many craft and sewing suppliers in packs of mixed sizes or as individual pairs of bars. I purchased a mixed pack of Sienna bars from Hobbycraft in the UK. My smaller designs are always sized to fit specific sizes of bar frames. Don't be tempted to buy cheaper brands as they are prone to snapping on the corners.