When you click on the settings gear on the upper right-hand corner, you will open a contextual menu, select advance. Under the installation tab, the lower left-hand corner, click the + button that will open a browse window to select and add your additional external runtime to the list. When you want to install your DAZ3D Poser content into that runtime, go up to Content Path Shortcuts and select the runtime you added to the app. Accept the setup.