That type of a stamp will have to be a custom (dynamic) stamp.  You can create and apply a dynamic stamp through an SDK Script activity, but since the LF Custom Stamp does not have available tokens for current page number and total page number, you will have to be a little creative. By modifying the sample code from Workflow Apply Stamp Limitations  you can create a script to meet your needs.

As an idea, in the LF Client, create a custom stamp called PageOf and set its text to be "Page %(CurNo) of %(TotalNo)"  The tokens will not resolve when applied through the LF Client (so make it private), but you can add Case statements to the sample code to replace the tokens.

In your workflow, you need to get the page count and then loop through and apply the stamp to each page.  You will need to add code to the start of the script to get the values for your total page count and your current page.  Then use those values to replace the tokens in the stamp.