Nice dash, and sweet use of SuperTiles in the upper left there.
As Josh illustrates, adding a Tile in ST to reflect the value of a Hub Variable should be exactly like adding any other device. So I'm not sure where the hangup is at this late stage. The fact that you're using RM instead of WC as the "back end" should not have any influence at all.
The Dashboard shown previously was a Sharptools Dashboard.
This post my Actiontiles Dashboard for my Computer or I can use it on my other tablets as I want.
After creating a separate RM Rule that turned on 3 separate Virtual Switches BarometerUP BarometerDown BarometerSteady I could see my new Rule was working. Then I went back to the original Rule I've been working on after seeing that I only needed 1 Variable Connector throughout the Actions and Sharptools, things started to work somewhat. However, Once I changed the Triggers in the Original, it is now working GREAT!!!
Pictured is a short Dashboard displaying both Devices from the Barometer UP,Down, Steady, and the Variable BaroTrendy.
Since Updating and creating the status of the Barometer Trend, I was able to add it to a Supertile in my Sharptools Dashboard for my larger tablet. Again, thanks to all the great input and guidance!