Apply the IBIS model with PKG parastic RLC in ANSYS Designer software

Hello All.

I am wondering for what should I use for the IBIS model including PKG RLC in Designer, Pin model or Buffer model?

There are 2 types of models in IBIS file, Pin model and Buffer model. If I want to use the IBIS model with PKG RLC while I run the DDR SI simulation in Designer, which model is right for? Pin model or Buffer model?

I Appreciate for your advice in advance...