Hi Bob,
As you probably found out, there is no direct import-export option from Roboform to True Key. The simplest way would be exporting your data to a browser that has this import option such as Chrome, IE or Firefox to import it back to True Key afterwards.
You can also try doing the same with another password manager that uses a CSV file to backup the data and that True Key recognizes to import it from them (Dashlane or LastPass).
As long as you are able to export your Roboform data in a way that the browser or the pwd manager accepts the format, then importing it to True Key through the TK settings- import page would be easy.
I hope this answers your question but please dont hesitate to reach back in acse of further questions.
Thanks,
Marc D.