Attach the Pink Generic Ruler Foot (GRF) to your machine by removing the screw holding your foot on the shank.  Adjust by placing a quilt sandwich under the foot and check that the fabric moves freely under the foot, then tighten the screw firmly.  Position needle in the centre.  You cannot lower the foot when the needle is raised, The Pink GRF is designed to work with 3mm rulers that are thin enough to pass behind the foot, so that you can make designs with the ruler.