I've looked all over for a place to see RH but I can't find it anywhere. I'm assuming it doesn't exist. As a paraglider, this is pretty important for me. It should be under meteogram in my opinion.
It is available under the temperature menu and you can see a value for a location when you click on the map and you can scroll left/right through time.
However it definitely seems like an oversight from the full chart you get when you click the down arrow to see the detailed view, I cannot find it there either. It probably should be added.