You mean to set eclipse-RCP-SDK as target platform, don't you?
Yes, it's a better pattern when developing Eclipse plugins to distinguish
between Eclipse IDE workspace (where you are coding YOUR plugins) and the
Eclipse target space (where rely all the tier plugins you are depending
on).
Just unzip RCP-SDK or platform-SDK in a folder an define your target
platform there. Then, also add the Subversive plugins in your target space
and you are done.
Remember that Subversive GUI won't work with RCP-SDK.
A good trick to test if your RCP app currently integrates all the desired
features/plugins is to use the [Help|About] menu. It lists them all
(search for "org.eclipse.team.svn*").