Short answer. With three things together: an affidavit of service by the person who brought the pleading to the service provider, the courier's official receipt, and the document tracking number. The rule requires all of them for a filing made through an accredited courier.
What the law says
(c) If the pleading or any other court submission was filed through an accredited courier service, the filing shall be proven by an affidavit of service of the person who brought the pleading or other document to the service provider, together with the courier's official receipt and document tracking number.
Rule 13, Section 16 — Proof of filing. Read the full provision →
Why this question arises at all
The starting point is that the filing of a pleading or any other court submission is proved by its existence in the record of the case. Ordinarily nothing more is needed. The rule's lettered paragraphs come into play only where the document is not in the record but is claimed to have been filed — which is exactly the position you are in.
The three items the rule names
For a courier filing, the rule specifies proof in three parts. First, an affidavit of service by the person who physically brought the pleading or document to the service provider. Second, the courier's official receipt. Third, the document tracking number. They work together: the affidavit establishes who lodged what and when, and the receipt and tracking number tie that account to the courier's own records.
Get the affidavit from the right person
The rule identifies the affiant with care — the person who brought the pleading to the service provider. That is often a clerk or messenger rather than counsel, and their affidavit is what the rule contemplates. An affidavit from someone who merely arranged the sending, or who is describing what they were told, does not match the wording and is a weaker document in any event.
Keep the record from the outset
Because the receipt and tracking number are prescribed proof, they should be preserved as a matter of routine rather than assembled after a document goes missing. The rule sets out equivalent methods for other modes: filing by registered mail is proven by the registry receipt and the mailer's affidavit, and personal filing by the clerk of court's written or stamped acknowledgment on a copy. Each mode has its own proof, so the mode you choose determines what you must keep.
What this proof does not establish
Proving that the pleading was filed is a separate question from whether it was filed on time, and from whether it was properly served on the other parties. The paragraph addresses the fact of filing where the document is absent from the record. Timeliness is judged against the applicable period, and the receipt's date is the evidence that ordinarily settles it — another reason the original documents matter. Service on the other parties is governed by its own provisions and requires its own proof.