Both crew MUST be rated......
....But just get the SIC to show up at your local FSDO with the paperwork for their 61.55 check and a completed 8710. they'll then be able to get a Temporary Airman Certificate (there and then) with a CE-680 SIC Type Rating on it.
Its actually written on the letter to which your plastic card Airman Certificate came attached; In essence it's an ICAO requirement and in europe if you're ramp-checked the SAFA inspection will be an ICAO spec ramp-check. Endure one without two type certificated crew and your aircraft will be going nowhere until you can produce such a crew.
Its also worth pointing out that they must have completed 61.55 requirements within 12 months and the PIC may not alternate types as provided under 61.58 (i.e. the last 61.58 must have been on the type concerned)
PM me if you have any problems or want any help with flying in Europe generally.