I found two articles in Duth newspaper, called ‘De Waarheid’.
The first one, from June 29th 1966, mentions that Simon & Garfunkel are in Holland for the TV recordings. And to introduce them a bit more to the Dutch readers, it tells us:
“…he [Paul Simon] brought a visit last year to The Netherlands during a tour. He performed in a TV show and recorded for the radio in Cobi Schreijers’ Haarlem Waag”
Cobi Schreijer indeed ran the ‘De Waag’, a theater, in Haarlem (near Amsterdam) and was hosting a radio show (as I was told a kind of ‘Five to Ten’) for the broadcasting company NCRV.
I know for sure that this is correct, as Cobi Schreijer has confirmed this to me and someone else spoke of a Guitar Master Class by Paul in ‘De Waag’.
For the NRCV Simon & Garfunkel would record their famous set for ‘Twien’, which was broadasted for the first time on August 12 in 1966.
The show was recorded three times. The first one was a repetition, the second a failed recording and the third went ‘on air’. The show now can be dated on June 30th, because the interview (published on July 1st 1966) was taken during the recordings.
After Holland, Simon & Garfunkel went on to England, Sweden and Denmark.
Paul Simon - 'Time it was...it was' 