Without checking, I guess this is the ID for the record of the resource rules for this service, ie how the scheduling engine should pick an appropriate resource. So it looks like you need this to be filled in and will therefore need to export those records
too (and include their GUIDs), and import both your services and the resource rules (resourcespec) records together. Usually this would be done by zipping the two csv or xml files together and importing the zip file as one.
Hope this helps.
Adam Vero, Microsoft Certified Trainer | Microsoft Community Contributor 2011
Blog: Getting IT Right