I've always used "Vicki". I'm not sure if that's accurate or not.
"Vicki" is the way it has always been spelled in the script outlines and scripts that I've seen. And it's spelled that way in all the official DS books. So, that's the spelling I've always gone with, too.
However, just because it's spelled that way in the scripts I've seen, that doesn't necessarily mean it's spelled that way in
every script. For example, the writers were notorious for changing the spelling of Windcliff seemingly at whim.
Most often it seems to be spelled "Windcliff" - but it's also been spelled as "Windcliffe" and "Wyndcliff" - and possibly even other spelling variations that are slipping my mind right now.