The option -d states:
-d dotfiles - Location of dotfiles, defaults to '~/.dotfiles'
But however inside the script the dotfiles path is built from $HOME/$DOTFILES, so to customize the dotfiles folder path one has to give the path relative to $HOME,
e.g. dotsync -L -f ~/.cronsync/dotsyncrc -d .cronsync
Consider changing the help message to avoid issues when using this option. :)
The option -d states: