OSF Saint Anthony Medical Center is expanding in Northern Illinois. OSF has purchased the former Byron Public Library bullding  at 109 North Franklin Street in Byron. OSF plans to renovate the 7,000 square foot interior and open the medical clinic in August. The office will house one OSF physician initially...with plans to expand to three doctors in the future.  OSF Saint Anthony is building a medical clnic/office complex at 4686 East Rockton Road in Rockton. Medical Center officials say construction will begin early next year with the target date for opening this August. The clinic will be designed to accomodate up to three physicians...with one doctor staffing the office initially.