Add the lemon juice and butter or margarine to the pot. Stir occasionally until the sugar melts completely on the medium heat. Once the sugar has melted, bring the mixture to a rolling boil
Add the liquid pectin and bring to a rolling boil once again. Cook fruit mixture for one full minute using a timer.Immediately remove the pot from the heat to your countertop. Allow mixture to settle and skim off the foam.
Fill your jars leaving ¼ of headspace. Wipe the rims of the canning jars with a damp paper towel and put the flat lid on. Screw your lid bands on. Process in a boil water bath for10 minutes.