Response spectrum analysis vs. equivalent static in AutoPipe

I always go with the equivalent static method, calculate the seismic response coeff. factor and input in AutoPipe as seismic loads in the X/-X & Z/-Z directions. Now I have a project the client wants to do a dynamic response spectrum analysis to confirm the system is ok. We all know the equivalent static method is using more stringent seismic load. I started defining the .SPC file using IBC 2006 method for the same location I initially calculate the equivalent static seismic load, so I have the acceleration vs. period load from the IBC 2006. In the equivalent static method the seismic response coefficient is SDS*Ie/R now I have to define the scale factor for each seismic load Ri, the default value is 1.0, if I go with the default value it will give a higher result than the equivalent static method as it is likely design for the equivalent full SDS, the scale factor I believe needs to be less than 1.0 but how to calculate or estimate is not provided by any AutoPipe example or descriptions in the help file. we need simple examples to show comparison and how to use each method available in the software and ensure that the software is correctly formatted and useful like what STAAD pro team do.