No, any leveling of the subfloor must be done prior to installing the DITRA-HEAT membrane. A major benefit of DITRA-HEAT is that self-leveling compounds are not required to encapsulate the heating cables, which results in reduced installation time. If desired, skim coating the DITRA-HEAT matting to snap chalk lines and/or protect the heating cables from other trades can be done using thin-set mortar.
For details about using self-leveling compounds with Schluter-DITRA-HEAT and Alternative Floor Coverings (AFCs), please see AFC Over Schluter-DITRA-HEAT Technical Bulletin.