The magnetic structure of erbium undergoes a series of transitions as a function of temperature and has a rich phase diagram. It exhibits a magnetic spiral and conical phase which could be technologically important if they can be utilised in thin film form in fields as diverse as spintronics and exotic superconducting pair generation. We propose to measure various, technologically applicable, thicknesses of erbium as a function of temperature on the PolRef reflectometer, both specular signals as well as tracking the τ spiral peaks. This will provide information on the effects of reduced dimensionality in the <10nm regime and allows us to further develop Er as a spin active material in applications.