Jumping on Friday to the reserves

Hello Rabbi,

A true story that happened:
We were called up to the reserves on Friday, June 13, 25, and all the signatures on weapons and equipment were spread out over the Sabbath.

The religious guys signed with their left hand, but there was also a religious officer who filled out forms and writing with his right hand (in his case, because he is left-handed) was unclear.

What do you think is the law in such a situation? Should I write as usual?