adobe signatures not accessible for keyboard users

Hello, I am wondering how to select the signature and add it to one's page without a mouse (with just one's keyboard)

I know one can  use shift F6 and then tab and then spacebar/enter to get through the tab pane to the signature, but it is not actually letting me select and add the signature to my document, i must still drag and drop with a mouse.  Does anyone know if there is a command  I am missing or if this is a general issue with PDFS?

p.s. shfit + f defaults to find rather than wht is listed in shortcuts, which is switching on tool pane. 

p.s. this submission form isn't accesible as i can't access the topics via keyboard or post via the keyboard.