How to request that collaborators add my supervisor's name to a manuscript I am collaborating with a foreign author. As I am still pursuing my degree, I have to add my supervisor's name in that paper, even though my supervisor has  not contributed to the preparation of this manuscript.

How should I ask my collaborator (foreign author) to include my supervisor's name as a third author? I need some help in this. 

Edited: As my supervisor has told me to add his name, I am obliged to add. I have no other options left. I am asking how should I write and request to my collaborator to include my supervisor name in the manuscript. Also, I am afraid whether my collaborator will feel odd or bad if I request him to do that.

Please help me: what should I say to my collaborator so that he may give third authorship to my supervisor?
While conventions vary greatly from field to field, if your supervisor has made literally no contribution, he or she should not be listed as an author. There is been plenty of discussion here of this issue; see e.g. 


Co-authorship for not very involved supervisor
When should a supervisor be an author?
What are the minimum contributions required for co-authorship