Regarding reference letter, digital signature, upload PDF in ACS

Hi ,

  1. My ex-employer provided reference letter in PDF which is digitally signed.
    If I send the PDF with digitally valid signature, the recipient receives PDF showing
    as “Invalid” signature.
    Will it be a problem in the ACS verification process.

  2. Digital signature doesn’t contain the designation of the signer, will it be a problem if designation isn’t specified in digital signature.

  3. While uploading in ACS, should we combine(copy/paste) reference letter, pay slips, form16 into a single PDF document while uploading a individual employment experience. Can anyone please provide any sample formats.?

please advice.