The RMn_12-xFe_x series of compounds of ThMn ₁₂ structure type exhibit rather complicated and composition sensitive magnetic properties. In the recent past, systematic neutron diffraction and magnetisation experiments allow to relate the main aspects of the magnetic structures to the polarisation state of the d band. X-ray magnetic circular dichroism (XMCD) analyses have been undertaken on iron rich compounds with R=Er, thus probing the L_2,3 edges of Mn and Fe as well as Er, and the M_4,5 edges of Er. These experiments permit to better understand the local magnetic polarisation of the different interacting orbitals versus temperature and applied field as well as to specify the nature of the magnetic couplings acting between the 3d metals.