Astro-Kundali PRO (Both Lite as well as Professional) have these useful tools for Birth Rectification.
In the Transits Screen there is a Birth Rectification check box. Whenever you want to do birth rectification you should click on this.
You have two methods for this.
1. KP- Using Ruling Planets:
Once
you click this the transits are plotted for the client's birth date and time and
Birth Place too. The time change interval is also set to 1 Min. Please note that
normally the transits are plotted for client's current place. Now using the
Up-Down button you can increase or decrease the birth time and then the planets
and lagna and charts will be plotted for these new times. You can use the
Hour:Min:Sec button too to change the time and then Click on the button 'Plot
for Time' to plot for the changed time.
Now using the Ruling Planets you may find the correct birth time.
2. Vedic- Using the Divisional Charts:
On the right hand corner of the transits screen there is a Combo Box with facility of changing to any of your chosen Divisional Chart. All the Time Changes will be reflected in that divisional chart. Now using the button 'B. Lgn Change?' you can find out the time for the earlier and later lagna change.