Because you signed a contract with a French company, you are required, in agreement to French Decree N. 2011-1601 signed on November 21th 2011 which purpose is to prevent undeclared work, to provide legal documents.
You need to provide the documents detailled bellow:
Certificate of incorporation or other legal proof of your company's registration, delivered by the appropriate authority in your country and no older than 6 months.
Certificate of payment of all national social taxes and contributions
If your contract is realized in France, you'll have to provide a listing of all outside UE workers names, nationality, date of hiring as well as legal authorization and legal authorization number.
If your contract is realized in a foreign country, you'll need to provide an affidavit stating that as a foreign company, you are not required to submit a foreign workers list.
For futher information about the documents required, we invite you to check the following website: http://www.cleiss.fr/employeurs/obligationdevigilance/index.html.
Accordingly to French Law (Art. D 8222-8) translation of your official documents need to be made by a sworn translator.