Roku elects Jeff Blackburn, former Amazon senior vice president-global media and entertainment, to its board ... DocuSign adds Anna Marrs, American Express group president-global commercial services and credit and fraud risk, to its board ... E-commerce tech company Rokt names Srishti Gupta, ex-Amazon, chief product officer, and Flatiron Health’s Josh DeFrain chief information security officer; Rokt also promotes Craig Galvin to chief revenue officer ... Ad tech platform TripleLift adds Tony Wells, former Verizon senior vice president-marketing and chief media officer, and Adolfo Villagomez, former Home Depot chief marketing officer-U.S. retail, to its board ... Tint, social content and community platform, promotes Susan Frech to CRO.