VAT is paid on sales by the seller to HMRC, if the seller is a not VAT registered then there cannot possibly be any VAT charged.
As a business buyer who is VAT registered you "may" prefer there to be a VAT element, if the buyer is asking for the receipt to include a VAT element (eg instead of £200 it is constructed as £167 + VAT) then this is illegal and dangerous unless the seller is VAT registered, it would be fraud.
A buyer cannot charge VAT nor pay it to HMRC on behalf of the seller.
In a time of universal deceit - telling the truth is a revolutionary act. George Orwell
When the debate is lost, slander becomes the tool of the loser. Socrates