var wb = new XLWorkbook();
var ws = wb.Worksheets.Add("Signatures");
// By default the signature will be with the logged user
// ws.Cell("A2").Comment.AddSignature().AddText("Hello World!");
// You can override this by specifying the comment's author:
ws.Cell("A2").Comment
.SetAuthor("MDeLeon")
.AddSignature()
.AddText("Hello World!");
// Set all comments to visible
ws.CellsUsed(true, c => c.HasComment).ForEach(c => c.Comment.SetVisible());
wb.SaveAs("CommentsSignatures.xlsx");