You can add up to 1000 external beta testers to your internal iOS project team. If you have several iOS or OS X projects and a long list of experienced external testers, you do not have to enter all of these email addresses each time you create a new application.
1. Open the iTunes Connect with your account at here.
2. Find your new application among My Apps
3. Click on Prerelease -> External Testers
4. Use + icon to add new tester(s)
5. Type in a new tester by adding his/her e-mail address and name or use Import File to add testers from a file. The file must be in .cvs form.
.cvs file can be created by a text editor and should look like this:
6. External testers will get an invitation email when new beta version is available and will be prompted to install the free TestFlight app from the App Store.
Important note: applications made available to external testers require a Beta App Review from Apple. 25 members of your internal testers can receive invitation to test any build version without this lengthy beta app review but they have to have assigned Technical or Admin role in iTunes Connect. See iTunes Connect -> Users and Roles.
first name, last name, email address
first name, last name, email address
for example:
Jane,Doe,jane@testersample.com
Joe,Dane,joedane@testersample.com