Hi,
if you want to get the SLP and geopotential height you should do the following postproc;
just go to the location of your output and then run the sigma2p execute program in the Bin folder in the RegCM-4.1.1 like the following

>/home/climate/RegCM-4.1.1/Bin/sigma2p climate_ATM.2001050100.nc

then you will have a file like climate_ATM.2001050100_pressure.nc variables hgt and mslp which you want to get.
i hope this will help
Regards