Does my work printing books for employees to use in converting salaries, which they use to obtain interest-based loans from the bank, count as participation in usury, knowing that the employee has the right to obtain this book?

If you know that the employee is taking out an interest-bearing loan, it is not permissible for you to give him a letter to the bank containing information about him and a pledge to transfer his salary, due to the assistance this entails in usury, which is forbidden.