Dear,
Please note JD for the same position may be different for different companies. Hence without knowing what all you want to include in JD nobody can help you out.
So simply note down the tasks that the person would be doing prepare the KRAs. Write every task in sentence like he/she would be responsible for arranging meetings etc etc.
Also note JD doesn't mean only KRAs. JD means complete details about the job. Hence shall include the following factors. ..
1) Functional Job Title.
2) Designation.
3) Band/Grade.
4) Reporting to.
5) No of reportees.
6) Age
7) Experience.
8) Salary.
9) Place of Posting.
10) Shift Timing.
11) KRAs.
12) Desired Profile.
13) Desired Competencies.
14) Personality Traits.
15) Interaction: External/Internal.
16) Educational Qualification.
17) Certification
18) Any Specific Requirements.