dTDP-β-L-rhamnose + β-D-glucosyl-(1,6)-α-D-glucosyl-(1,2)-β-D-glucuronate-(1,2)-α-D-mannosyl-(1,3)-β-D-glucosyl-(1,4)-α-D-glucosyl-diphosphoundecaprenol → β-L-rhamnosyl-(1,6)-β-D-glucosyl-(1,6)-α-D-glucosyl-(1,2)-β-D-glucuronate-(1,2)-α-D-mannosyl-(1,3)-β-D-glucosyl-(1,4)-α-D-glucosyl-diphosphoundecaprenol + H+ + dTDP