sign_timesheet.py

import pypdf
import glob
from pathlib import Path

files = "2022/*/*.pdf"
with open("Unterschrift.pdf", "rb") as overlay:
    for file in glob.glob(files):
        with open(file, "rb") as inFile:
            original = pypdf.PdfReader(inFile)
            background = original.pages[0]
            foreground = pypdf.PdfReader(overlay).pages[0]
            
            # merge the first two pages
            background.merge_page(foreground)
            
            # add all pages to a writer
            writer = pypdf.PdfWriter()
            for page in original.pages:
                writer.add_page(page)
            
            # write everything in the writer to a file
            outpath = "out/" + file
            Path(outpath).parent.mkdir(exist_ok=True, parents=True)
            with open(outpath, "wb") as outFile:
                writer.write(outFile)