Free Agent Retention Question

I know that if you are the prior owner of a free agent and another player wins the bidding for them that you are given the option to offer them a contract for one year more than what the winning bid was (for example, if the player was a WR and another team won the bidding for say $50 which equates to a four year contract, the prior team would be given the option of retaining him for a five year contract for $69). What i'm wondering is, in that scenario what would happen if the winning bid was for a seven year contract, say in this example of a WR, $130? What amount would the player's prior team be required to pay to keep his services, as there's no such thing as an eight year contact tier?

You pay a bonus over the offered contract and sign them to a 7 year deal. I think the bonus is between 10 and 20%, without looking at the code.

This is a very good question, in as far as the retaining team only has so much money left...if they can't afford the 10-20%, which is quite a difference in itself. 10 or 20% could be quite a bit in the real money difference.