Are you asking about the Payer's TIN; i.e., Vanguard?
We can't see your 1099-R, so we can't tell you "where" it is on the form, but can tell you a couple of possibilities. For your security, do NOT post an image in this public Internet forum.
If it's a standard 1099-R using the official IRS form, the Payer's TIN is right under the Payer's name and address. This is the most common situation.
However, brokers/financial institutions may use their own proprietary form for their 1099's instead of the IRS standard 1099-R. If it's a non-standard form, look it over carefully. It may not call it a TIN. It may label it as the Payer's EIN or "tax number", etc. If it's a non-standard form and there's any question about it, you'll have to phone Vanguard customer support and ask them to tell you where it is on the form.