Copy the text of the "Rugăciunea înainte de citirea Sfintei Scripturi" from a reliable Orthodox prayer book. Paste it as the first page of your PDF using a PDF editor.
Some PDFs include footnotes or commentary from Reformed or Evangelical sources. An Orthodox reader needs the interpretation of the Holy Fathers. A better PDF either has no notes (clean text) or notes from Orthodox sources (e.g., Bartolomeu Anania’s translation). biblia ortodoxa pdf better