Hi,
Please read the wrapper user guide (docs/rttov-wrapper.pdf), in particular section 6 which describes pyrttov interface, and section 6.4 which describes how to specify input emissivities and reflectances.
By default pyrttov sets the RTTOV calcemis(:) input array to true, so you may not need to do anything. It is controlled by the SurfEmisRefl member array of the Rttov class. If the relevant elements are positive values then these are used as input emissivities, otherwise the corresponding elements of calcemis(:) are set to true. The wrapper user guide gives full details.
Best wishes,
James