The formula with the DR part in it is for a mature company - a combination of Debt and Equity which is equal to (1-Debt) are used to pay for the Investment in WC and FC.
So of the WC amount spent to buy Working Capital -> (1-DR) * WC is equity spend, while DR * WC is the Debt Spent (Net Borrowing Part).
When it comes to FC - you have a portion that you actually do not spend which is the Depreciation Part. So (1-DR)*(FC-Depr) = Equity Spend on FC, while DR*(FC-Depr) = Debt Spend (Net Borrowing).