How to add frequent words of each document in the result of word lists?

If you want the words per document you need to create a special label attribute, easiest can be to generate an id first with the 'generate id' operator (but tick create nominal ids).

Next change role with the 'set role' operator from 'id' to 'label'. 

Now you will have all words per label, or in your case by document. 

@kayman
It doesn't work. Do you mean this process?
please correct me, if I'm wrong.

You need to generate the id (and label) before the process documents operator, as this operator needs the label to 'group' your words. 

You will also need to use the wor (wordlist) output of the process documents operator, asthis will provide the expected format

@kayman It's working as you told me. Thank you so much