As far as I am aware to renounce your PR status all you need are photocopies of the Bio info pages of your passport.
A PRTD is only for specific travel purpose, limited validity and not really relevant to renouncing PR. If you feel more comfortable with the renounce paperwork you can include a letter of explanation mentioning the lack of PR card and having a PRTD.
I guess you have your reasons for renouncing after just 4 months and then taking a gamble that a new EE application will succeed but as everyone here will suggest renouncing should be a last resort, especially as you probably know you can stay away for near 3 years before it becomes a problem.