Will forgery on white paper pertain to a crime of forgery.
Yes. He knew that the document is not genuine. He used this document to attempt undue benefit fropm employer.
He did not gain anything by doing this .
Not relevant. He made an attempt and offence was complete when when he produced this documents with intention to get the incentive not entitled. Many theives get caught before decamping with booty that does not mean that they are not thieves.
The media through which he committed this crime has been seized. This is happened almost a year back and the case has been filed by the firm concerned and not the firm which he worked for.
It appears from your wording that you mean the company whose signature was forged has filed the case.
Both the companies are victims. Any, each or both can file case against him.
What is the way out of this legally?
Begging for mercy is the only way out as suggested by Mr Limeye.