The Spanish Football Federation president was filmed grabbing and kissing Hermoso without her consent after Spain beat England 1-0 in the World Cup final.
Rubiales has since faced numerous calls to resign, with FIFA and the Spanish government both launching investigations into his conduct.
He has repeatedly maintained his innocence, doing so most recently on Friday.
Dortmund fans, though, made sure to send a message of support before they faced Heidenheim in the Bundesliga Friday evening.
They revealed a banner reading: "We believe you sister, Solidarity with Hermoso."
FIFPRO, the players union, also released a statement on Friday insisting that female players have been let down by federations across the globe. Dortmund went on to draw the game with Heidenheim 2-2, despite taking a 2-0 lead within 15 minutes.