H2O offers no support for importing/exporting(*) pmml models.
It is hard to offer a good suggestion without knowing your motivation for wanting to use both RapidMiner and H2O. I've not used RapidMiner in about 6 or 7 years, and I know H2O well, so my first choice would just be to re-build the model in H2O.
If you are doing a lot of pre-processing steps in RapidMiner, and that is why you want to use it, you could still do all that data munging there, then export the prepared data to csv, import that into H2O, then build the model.
*: Though I did just find this tool for converting H2O models to PMML: https://github.com/jpmml/jpmml-h2o But that is the opposite direction for what you want.