pdf file, how to annotate?

I have been sent a form ti fill out in a PDF format. I can use this in windows no problem, but I am having difficulty in typing on the form on my IMac. When I open the document and select comments, insert text at cursor I get a box open up with a blue tail ending where I placed the cursor but when I type in the box nothing comes up in the document. Help

Not a "Switcher" topic. Moved here to "OS X Apps....." where it belongs. Also modified your title for clarification.

OK chscag thanks

Which application are you using? Have you tried using Adobe's Reader program?

The file opens in Adobe Acrobat Pro no I have not yet tried Adobe's Reader will have a look

Yes that works thanks vansmith