Complex sentence: Rappaport was in his studio when Tom Kalenderian, then Executive Vice President of Barneys New York visited to shop his neckwear line and suggested the showing.
Split into simpler sentences: Rappaport was in his studio when who at the time, was the Executive Vice President of Barneys New York. During Tom Kalenderian visit to David Rappaport's studio to shop his neckwear line and suggested the showing.