Usually our site supervisor will take some amount as advance to spend out at the project site. Later after a week or two they will pass over all the invoices for the advance money which they had spend out. My questions are?

1) How do I put in the entries for the advance taken?
2) After recording and post to system all the expenses incurred, how will I know whether the site supervisor has to return any balance of advance taken OR I need to pay him for the excess amount he had spend?
Thank you

One way of doing it would be to set up an account for the site supervisor in accounts receivable under 'other debtors', then:

Dr Site supervisor - cash advance
Cr Cash/Bank

With the amount of the advance.

Then when they provide receipts for purchases:

Dr whatever expense accounts
Cr Site Supervisor - cash advance

Once the receipts are processed, the balance (if any) on the cash advance account will tell you whether they owe, or are owed, money back. If the balance is a debit, then they haven't spent all of the advance.

And, probably goes without saying, but make sure they sign a form or log in acceptance of the amount of the advance given to them.