If I understand what you want, you want to have FILE1.RTF and FILE2.RTF and combine them into NEWFILE.RTF????
Currently, it is my understanding that this is not possible because of the structure of an RTF file. According to the RTF specification, there are fixed control strings that signal the top and bottom of a single RTF file. According to this Tech Support Note: http://support.sas.com/kb/24/034.html
RTF files cannot be appended together.
However, having said that about not being able to combine RTF files with SAS, it is possible inside Microsoft Word, to open FILE1.RTF and then, inside Word, to insert FILE2.RTF and to save a new Word document that is the combination of those 2 files.
Also, within SAS, you can do this (using code):
ods rtf file='threeproc.rtf';
proc print data=sashelp.class;
proc freq data=sashelp.class;
proc univariate data=sashelp.class;
var height weight;
ods rtf close;
...and the output from all 3 procedures will be contained within 1 RTF file.