Catalyzes the transfer of the first rhamnosyl residue on p-hydroxybenzoic acid or phenolphthiocerol derivatives to form, after O-methylation at position 2 of the sugar unit, mono-O-methyl-glycosyl-p-hydroxybenzoic acid derivative (p-HBAD I) and 2-O-methyl-rhamnosyl-phenolphthiocerol dimycocerosate (also called mycoside B) during p-hydroxybenzoic acid derivatives (p-HBAD) and glycosylated phenolphthiocerol dimycocerosates (PGL) biosynthesis. Belongs to the glycosyltransferase 28 family.