PDFDoc source("path_to_source_pdf");
source.InitSecurityHandler();
pdfviewctrl->DocLock(true); // if viewing the target document, lock it first
PDFDoc* target = pdfviewctrl->GetDoc();
Obj* src_annot = source.GetPage(1).GetAnnot(0);
SDFDoc* sd = target->GetSDFDoc();
src_annot->Erase("P"); // erase reference to source page, to prevent importing more than what is needed
Obj* dest_annot = sd->ImportObj(src_annot, true);
Annot new_annot(dest_annot);
target->GetPage(1).AnnotPushBack(new_annot);
// calculate new position on target page
new_annot.Resize(new_rect_position); // Important!
pdfviewctrl->DocUnlock(); // unlock
pdfviewctrl->Update(new_annot, 1); // refresh page