Unfortunately, you cannot configure the persistence service(s) using the Paper UI (or another GUI) (for now? )
You can only set the default one in Paper UI → Configuration → System → Persistence → Default Service
You will have to work with flat configuration files. You will need to use 2 files for RRD4J persistence:
/etc/openhab2/services/rrd4j.cfg
& /etc/openhab2/persistence/rrd4j.persist
(assuming you are on a linux apt-get installation)
By the way: openHAB 2.0.0 Stable Release is already out. You can get it from here: https://bintray.com/openhab/mvn/openhab-distro/2.0.0
http://docs.openhab.org/installation/index.html
and if you are interested in advanced graphing stuff, take a look @: