I frequently annotate PDFs and need to indicate where text is to be inserted. I know it can be done with a popup but the symbol is large and it is not a standard proofreading mark.
Other programs (including, but not limited to, Acrobat) use a colored caret (^) to indicate the place where text is added. Here is an example:
Please consider adding this standard proofreading mark. It’s one of the things that is preventing me from adopting Okular to read and annotate PDFs routinely.