missing jar by migration custom application to 7.3

Hi experts,

I am migrating a custom application from NWDS 7.0 to NWDS 7.3 and I get an import error for RID.

Could someone tell me which of the standard Used DCs I need to use for this? Or where I can find the jar file?

IResource resSearchFile = (IResource) ResourceFactory.getInstance().getResource( new RID(strDir + "/" + strFileOld),

(RID cannot be resolved to a type)

Thanks in advance,

Vo