Bild per Druck mit Kreuz markieren

Google translate: I would like to put a field in a PDF file over a picture, in which I can mark any place by printing with a cross (X). How is that possible?

If you just want to add X's to your PDF, the easiest way is to use the comment tool to add a stamp or custom stamp.

You can also add a form field check box, where you can right click to access the check box properties> Options> Cross, however you will need to select the form field to add the X (you can't click anywhere).

A third method involves using buttons and layers, which I would do using InDesign, although it might be possible using Acrobat alone.

Briefly, you would make an invisible button on top of each picture, when the picture was clicked (anywhere) the button would turn on a hidden layer, which would display your X in a pre-determined size and position. If this is not what you are looking for, can you please elaborate?

Note, not all PDF viewers respect layers, buttons & forms. Acrobat or Adobe Reader will work well.