I too have come across this before, hopefully someone else has too and can point us in the right direction
Added the meta tag to my layout:
<META HTTP-Equiv="SIP" Content="Automatic" />
This enables key board when going into input field, and to put it down just de focus the input.
Works like a dream for me and has solved my issue.
Setting to Automatic worked for the specific case I had. Is it possible to have the keyboard moved up a bit to make sure it's possible to see the bottom menu bar at all times?
One clever work around is to assign one of the program buttons to open the SIP and close it. I was working on a Honeywell 7800 PDA and this was very easy to do and worked perfectly.
Has anyone tried this in RMS 4.0? I'm curious whether it has been fixed. Will be trying this later on this week. Will update when done.