If you don’t have a grater, there are a couple of options to work the butter into the flour mixture. If you have a pastry blender, you can keep the butter cold (but not frozen) and cut it into pieces. Use the pastry blender to cut the butter into the dry ingredients until the mixture resembles a coarse meal. You could also use a food processor to pulse the butter into the mixture. You can use frozen butter for this, but cut it into pieces before adding it to the food processor. If you use your food processor, transfer the mixture into a bowl after pulsing in the butter so that you can follow the rest of the recipe as written.