ant = page:CreateLineAnnot(text, encoder)
page:CreateLineAnnot() creates a new line annotation object for the page.
Nil, the default encoding is used#HPDF_INVALID_PAGE - An invalid page handle was set.
#HPDF_FAILED_TO_ALLOC_MEM - Memory allocation failed.
#HPDF_INVALID_ENCODER - An invalid encoder handle is specified.