We have developed an experimental approach using a buried magnetic layer to provide contrast in systems consisting of complex biomolecular layers tethered to gold surfaces. This has centred around two outer membrane proteins (OmpA & OmpF) which act as ion channels in the bacterial membrane. Simultaneous fitting of slab models to the datasets has achieved high resolution information on the structure and compositions of the layers. As the interfacial structure becomes more complex and we tether larger proteins from solutions making interfacially anchored proteins complexes with size in excess of 250 kDa assignment of slabs of density in the structure to discrete components becomes more problematic. Model independent direct inversion of the data should be possible. POLREF & OFFSPEC offer the potential to access higher Q ranges significantly improving the quality of the inversion process.