The dough for focaccia is soft and tacky. To fit it into the tray, use oiled hands and gently stretch the dough to expand it, so it is large enough to cover the tray. Rest the dough for 10 minutes. The dough will shrink back on itself. Repeat stretching; leave it in a warm place for 1 hour. Poke dimples into the surface of the focaccia with your fingertips for 
its characteristic look.