If I lose a receipt, is a perjury statement a valid form of documentation on a sponsored award?

No, perjury statements are not a valid form of documentation in lieu of a lost receipt. 

If a receipt is lost, all efforts should be expended to obtain a replacement receipt from the vendor. If a replacement receipt cannot be obtained, and the cost of the item is greater than $75, then the cost must be charged to non-sponsored funding. 

Please see PAFC Documentation Guidelines