// in radrails when you import a project from subversion
// it is a normal project

// in the menu I found no way to transform it
// but so it worked for me:

// 1. edit the .project file and copy the natueres block

	<natures>
		<nature>org.radrails.rails.ui.railsnature</nature>
		<nature>org.rubypeople.rdt.core.rubynature</nature>
	</natures>

// 2. copy the buildSpec block too
// (I'm not sure if this is necessary, I did both and it worked)

	<buildSpec>
		<buildCommand>
			<name>org.rubypeople.rdt.core.rubybuilder</name>
			<arguments>
			</arguments>
		</buildCommand>
	</buildSpec>

// 3. restart radrails and
// 4. add a webrick-server to the project
// and you are done

From: http://lists.radrails.org/pipermail/radrails/2006-February/000313.html
Just hit Restart and it will actually be started. Then you can stop it. If
all else fails, delete the file

workspace/.metadata/.plugins/org.radrails.server.core/.servers.