Certificate of Employment/Proof of Gap for KLC

Hello! I’m planning on applying for the Regular Program and will need a D4 visa this upcoming application cycle.

For those who did the same, what type of documents did you send/were accepted by KU KLC proving your gap after graduation and current employment?

I worry a bit about my job if I were to ask HR for a verification of employment and I’d tell them it’s to go study abroad (since I need to stay at my job until I’d leave for Korea), would my job offer letter work?

I doubt a resume would work for the proof of gap as well, what are ways that have worked for others?

Thank you for any help/advice!!