Selecting the Link to File option does not store the audio clip as part of your presentation but links to it. If you cannot find the Link to file check-box, click the Options button, highlighted in blue to reveal this option. To maintain maximum compatibility across operating systems, it's best to use the MP3 file format for audio files.
Similarly, AIF (AIFF) files can be inserted within Mac versions of PowerPoint but do not work in all but the recent Windows versions of PowerPoint, and even then, you may have codec issues. However, WMA files can be inserted in Windows versions of PowerPoint. Navigate to the folder where your audio clips are saved, and select a file.
You can also insert audio into your slide through Audio Browser, the other menu option you can see in Figures 1 and 2, shown previously on this page.