Delta Load from the last successful ETL run

We are trying to build our report in Rational Insight 1.0.1. We have a reportable REST service in RTC and we have to use XDC to populate a star schema using Datamanager in the DB2 data warehouse.
Here we would like to know if we need to fetch delta records from the last ETL successful run. Can anyone suggest what is the best way to achieve this via DataManager?
Here we would like to know if we need to fetch delta records from the last ETL successful run. Can anyone suggest what is the best way to achieve this via DataManager?