Yes, it is possible. The RMS itself doesn't offer I/O management, but if the device connected to RUT955 has WebUI, then it can be reached through RUT955.
If you would like to connect to your external device through RMS, then you should follow these instructions on RMS:
1. Add your router to RMS;
2. In the bottom near the router on "Actions" section click an information symbol to open detailed information;
3. In the top menu ribbon click on "Actions" section to droplist and select "Access";
4. In the device access window click the "+" icon to add the device you would like to reach;
5. Enter all the information required;
6. Scroll down to the bottom to find table with added devices and click on the one you just added;
7. Click on "Generate view" to create a token with the link to connect to your device.