Signature text box and hot keys

[defaultpv0ocebe0omd]

So I love hot keys and I use the fill & sign text box feature a lot to allow me to write something and not have it changed by others. I recently discovered how to get to that option using the hotkeys; however, when I select the function I can't figure out how to "Click" on the document and actully add the text without using the mouse. Can someone explain to me the hot key way for clicking on a document and using this function?