can i sign a document in blue
I think you are asking in the wrong place. This forum is for printed documents that have been created using Adobe's RoboHelp product. Your question does not look as if it is related to that.
See www.grainge.org for RoboHelp and Authoring information
I noticed that on the forum page, if you look at the More Like This section to the right of the post, a couple of posts in other forums seem to be asking the same question. One of those might help you.