Final answer:
The best audit procedure is to develop a program to compare account balances with credit limits and identify accounts exceeding these limits for efficient and systematic review.
Step-by-step explanation:
To determine whether credit limits are being exceeded in Smith Corp.'s customer file, the best procedure for an auditor to follow would be to develop a program that compares credit limits with account balances and print out the details of any account with a balance exceeding its credit limit. This technique allows the auditor to efficiently review all the data, rather than a sample, and immediately identifies any discrepancies. It is a more sophisticated method compared to manually checking account balances and provides a systematic approach to error detection.