can i find it here in switzerland a JAR examiner
The one thing you need to remember when using a non-UK JAR examiner for a UK JAR revalidation is that that examiner will not be known to the UK CAA.
I don't know if it's an absolute requirement, but at the very least it's a good idea to make a copy of the examiners license, which should clearly show the classes he's rated for plus his Swiss registration number, and send that copy along with the other paperwork.
If your friend is a class rating *examiner* (CRE) for the appropriate class (SEP probably) then he's able to sign for your revalidation. A class rating *instructor* (CRI) would not be enough.