How to define custom runConfiguration or runConfigurationFactory in plugin.xml file? (if needed)

Hi, I have created my own runConfiguration and runConfigurationFactory and I think I need to define it in the plugin.xml file but I don't know how to do it. I tried to add it by runConfiguration and runConfigurationFactory tag in extensionion tag but these tags are not there. Does runConfiguration need to be defined in plugin.xml? Because my custom runConfiguration is not added to project run settings.