The general principle of bookmarks and ref fields will still work, but the
requirement to append the input to a data file converts this from a simple
task to a more complicated one. Essentially you would run a macro on exit
from the last form field used, to gather the data from the bookmarks and
then write it to another document. If you start with a blank document called
(say) names.doc and you have two fields called Text1 and Text2 then
something along the lines of

Dim sName, sAddress, sOutput As String
sName = ActiveDocument.Bookmarks("Text1").Range
sAddress = ActiveDocument.Bookmarks("Text2").Range
sOutput = sName & ", " & sAddress & vbCr
Documents.Open FileName:="Names.doc"
Selection.EndKey Unit:=wdStory
Selection.InsertAfter sOutput

would add your field content to the names.doc file. It needs work to produce
a useable function, but it should set you on your way - there are plenty
of vba enthusiasts active in the Word vba groups if you need further help
with this.

A more elegant alternative would be to create a userform to gather the data,
but the principle is the same. There is lots of information on userforms on
the MVP web site (link in sig. block) to get you started with this.