Internal method documents with revision history, the technologist's training and teaching records, examples of work product that depended on the protocol, and a written comparison against standard published methods. General experience in the field does not qualify on its own.
Document the difference, not the expertise
The statutory definition asks for special knowledge of the company's own service or techniques, or advanced knowledge of its processes. A reviewer will assume the technologist is a competent hydrogeologist and look for what distinguishes him from another competent hydrogeologist hired locally. The evidence that answers that is internal: the protocol manual with its version history, the training log showing when he was certified on it and when he began training others, and records of client or regulator submissions where the protocol's validation steps were relied on.
Pair those with a short technical comparison explaining how the company's method differs from the standard guidance a U.S. hire would already know, and an estimate of the time and cost to train a replacement. Be careful with confidentiality: agree with the company what can be disclosed and redact commercially sensitive details rather than withholding the documents.
Do not attach a pile of field reports without explaining what they show. Hypothetical example: A fermentation-equipment company transfers a specialist who knows its internal cleaning-validation sequence. The first review should select a small set of dated manuals, training records, internal approvals and work samples that connect that person to the sequence.
An authenticated training log and a supervisor declaration settle participation more clearly than a résumé alone. Explain any redaction in a cover index, and preserve the page references that let a reviewer follow the progression. The common mistake is submitting proprietary material without a plain-language explanation of why the knowledge differs from ordinary industry practice.