John,
SPP can do Reorder Point Based planning in DRP.
Product Location Master --> DRP Tab --> DRP Planning Mode select the "ROP".
SPP DRP will calculate the Max stock and Reorder point for you or you can enter the values manually as well
You can control in configuration how long the planning mode should remain ROP and at which point ROP should get changed to Forecast based. For this you need to run special PSM service as well.
Note - ROP based planning will not consider forecast during its planning.
Just my thoughts
Vinoth