To insert reusable actions you need to select "Insert -> Insert existing action..." and use the dialog to specify the action to call. You can't just put a line saying "RunAction some_action, 1 iteration". You'll get error that way. QTP need to build some internal links between the calling and called actions and that's why you need to use the UI to call an action.
When the Dialog that lets you select the script to call the action from opens, change the absolute path of the script to a relative one.
To change the paths of already existing actions, use the 'External Action Call Modifier' utility that comes with QTP Plus. Again, you can manually replace the absolute path by a relative one or browse and click away.