You need to find out if the puckering is coming from the hoop not holding it tight enough or from not having a heavy enough stabilizer.
Take a hoop and load it with the stabilizer of your choice and some scrap fabric. Draw a pencil line around the inside of the hoop..then stitch the design out.
When you're done..if your pencil lines have shifted to the inside of the hoop, then you have a hoop tightness problem..there are many fixes for this on the internet..just google it
If your lines stay put and your design puckers, then you need a heavier stabilizer.