I had a search and wasn't able to find anything about this so thought I'd post it as an idea of my own:
As far as I know, there is no way to complete the dimension command other than clicking where there are no references. Sometimes this can be hard to come by without zooming out and finding a spare bit of space. As an MEP user, I find this to be a pain and whilst it isn't insurmountable, it would be nice to just hit a finish button when you have finished selecting all of the references you would like the dimension to associate with.
I am currently working in Revit 2016 but am unaware that there have been any changes to the dimension tool in later versions.
Please provide feedback to me if you have already seen this topic posted here as I must have missed it!
I know this is a small thing and I might just be doing it wrong, but if it's so small, but adds QOL (Quality of Life) then I think it is worthwhile adding into the program.
Kind regards,
Ben