How to take incremental backup for set of datafiles then continue for another sets using RMAN

Hi guys,

I have Big DB size, which is not synch with its standby, Also quite few days archive logs are missed in primary, since we do not have enought space in OS level in primary to keep RMAN backup sets,Hence we need to take incremental backup for set of/few datafiles from primary then restore into standby, then another set of incremental backup from primary then restore in stand by then need to be done recovery in standby in order to make synch using RMAN.

could you pls. guys guide me how to perform above process in step by step with syntax , along with that is there any other way can be fllowing for my situation(if oslevel less storage,note able to keep all the datafile incremental backupP, could you pls. advice me on those steps as well. also how do I get estimated backup space requirement as well.