Hello Veeranjaneyulu G,
Have you looked at the gstreamer1.0-plugins-good package? Most of the RTP plugins are contained there. You may find more details on how the plugins are classified on each package on the following document from Freedesktop:
http://gstreamer.freedesktop.org/documentation/plugins.html
As for how to add the packages to the local.conf file, you may do so using INSTALL_IMAGE_append as follows:
IMAGE_INSTALL_append = “ gstreamer1.0-plugins-good”
I hope this helps!