The Reason installer adds a single version of Reason Rack Plugin to Pro Tools, and that is found under the Instruments sub-menu. However, it can also used as an effect plugin. To add Reason Rack Plugin as an effect to a track:
1. Click an Inserts slot in the track list or Mixer view.
2. On the menu that appears, find the Instruments sub-menu and select Reason Rack Plugin.
When the Reason Rack opens, a palette of Instrument devices is shown, but now we want effect devices:
3. Click "Add other device" near the bottom of the rack.
4. Either select "Create Effect..." (and continue in the Browser) or select a device from the "Effects" sub-menu.
When an effect device is added it is automatically connected to the main inputs and outputs of the Reason Rack. To see this:
5. Flip the rack by clicking the button at the top, or by pressing [Tab].
6. Unfold the I/O Device at the top of the rack by clicking its fold arrow button to the left.
As you can see, the effect device has been added between the main audio inputs and outputs.
Playing back the Pro Tools track will send the audio through Reason Rack Plugin and through the effect device you added. You can add more devices to create a chain of effects - they are automatically routed when you add them.