If possible the Hongbao is preferred to contain RMB, but other currencies should be a viable option to if you are unable to obtain RMB. Depending on your identification with your lineage the Hongbao should include different amounts of money. For a complete stranger, the Hongbao is a very respectful approach, and less money is expected – depending on the occasion the envelope contains around ~50 Euros. If the person is closer to the Shifu (in a student – Master relation), the red envelope may contain between 100 and 300 Euros. These are rough estimates and are not an ultimate rule.