In Pennsylvania when refuse blood test are they required to have a witnesses to refusal and reading of 1547

When you have been asked to submit to a blood test in connection with a driving under the influence case the officer is required to read you an O'Connell warning which is set forth in the Section 1547 you referenced.  As part of this process, you are required to complete a PennDOT DL-26 form in which you acknowledge the warning.  If you refuse to submit to the blood test, the officer completes the requisite section indicating so.  No witness is required.