Just installed the plugin atop Redmine 1.3; seemed to install fine, but the custom field was not automatically created.
Moreover, I can't add the custom field myself. I select format of "googledoc" but upon submit receive the error:
"Format is not included in the list."
I tried Guillermo's solution from this thread -- http://www.redmine.org/boards/3/topics/19660 -- but the "disabled" issue he mentioned was not present in my install, so no dice.
Same problem with me. I am on redmine 1.2.1stable. Did you find any solution for this.