叫老闆簽文件，英文點講？

May I have your endorsement on this document please?


or

May I get endorsement if you found this document is acceptable?


or

May I have you to sign (your name) in the space marked for endorsement please?


or

Please kindly sign this document as for endorsement.


or

Can I have your signature for this document please?

2009-02-02 14:36:18 補充：
Sorry, a typo on #2 ...

May I have your endorsement if you found this document is acceptable?

Please sign this document.

叫老闆簽文件，英文點講？
Documents: such as P/O, L/C application or bank paper etc.
Please sign & approve these documents, they were checked & found correct.
Letters or invitations:
May I have your signature then I'll send by post afterwards.
Note:
不用說太多客氣話, 達意便可, because you are working & not asking for a favor.

Colloquially speaking, just simply :-

a. (For outgoing correspondence, important documents etc) - For your signature, please.

b. (For minutes, minor reports and other general documents) - For your endorsement, please.