N.B. @wapiti with PostFinance you pay 2 CHF to them plus another 6 to 12 CHF to the “intermediary”, depending on how much you transfer (according to their hotline it should be 6 CHF up to 10k and 12 CHF above it).
I transferred 10k and received 9.994 on IB. The 2 CHF commission are then subtracted from your PF account at the end of the month.