Dated project records, escalation histories, internal design or procedure documents the person authored or maintained, training material they wrote, and manager statements pointing to specific work. Add the employment history abroad covering the relevant period, and corporate records establishing the relationship between the entities. Volume is not the aim; traceability is.
Prefer traceable records over volume
Archived material from a long career is often scattered across superseded systems, former teams, and departed managers. Decide early who can retrieve what, and accept that some evidence will be a current manager's account of past work rather than a contemporaneous file. Label those honestly rather than dressing them up.
A short set of dated, specific records supports the description better than a large folder of routine output. Decide early who drafts the knowledge description, because the strongest version is usually written by the manager who calls this person in, not by a central function working from a template. Ask that manager for two or three named incidents with dates and outcomes, then let a specialist shape them into prose.
Where a record has been lost with a superseded system, note that on the index rather than substituting a general statement that implies a contemporaneous document still exists. Hypothetical example: a fermentation-process specialist's file rests on three dated deviation investigations they led, each with its internal report reference, rather than on a decade of routine batch sign-offs.