There are lots of tool available on web for conversion of MS Outlook PST to IBM Notes NSF format. Here I suggest all users before using any tool to first try the manual solution through which you can easily export entire PST file data to NSF. I have also used manual solution and I am fully satisfied of their conversion. So I would also like to recommend the same.
For more details about manual conversion procedure, here:- http://migrateemails.com/2015/09/03/how-to-convert-outlook-pst-files-into-ibm-notes-nsf-database-file/