Informant Sync calendars are the only calendars that can be exported from within the Pocket Informant app. Exporting a Google calendar to iCal or an iCal calendar to Google is not possible within Informant.

Open Informant Settings>Calendars, Triggers, and More>Manage Calendars. Tap the calendar you'd like to export and tap the "Send" icon in the lower left. Choose to send this file to your email. This will send your events to your email in the form of an ics file. Save this file to your computer.

To import your file into Google, open up your Google Calendar online. Select the cog icon in the top right and go into your Settings. Select Import or Export. Choose import and select your ics file. This will import your event into your chosen Google Calendar.

To import your file into iCal, open up your Apple Calendar on your Mac. Select File at the top of the screen and then select Import. Tap the ics file and select the calendar you'd like to add the information to.