You Can get smart form output in PDF format by writing a 
executable program with HTML Viewver.

Steps:
1. Create a Screen '100' for your program and create a 
Custom Control with name PDF.

2. Data diclaration for HTML Container:
data:g_html_container type ref to cl_gui_custom_container,
     g_html_control   type ref to cl_giu_htm_viewer,
     lv_url type char(255).

DATA : l_job_output_info TYPE ssfcrescl.
DATA : ls_control_param  TYPE ssfctrlop.


3. Fill ur data in internal table and call your smart form.
    Pass Values to Smartform
 CALL FUNCTION '/1BCDWB/SF00000166'
    EXPORTING
     control_parameters     = ls_control_param
     e_tpseg_start_date     = lv_e_tpseg_start_date
     e_tpseg_end_date       = lv_e_tpseg_end_date
   IMPORTING
     job_output_info        = l_job_output_info
   TABLES
     et_trip                = lt_trip
   EXCEPTIONS
     formatting_error       = 1
     internal_error         = 2
     send_error             = 3
     user_canceled          = 4
     OTHERS                 = 5.

You will Get data into OTF Format in "l_job_output_info".

3. You have to convert Data in PDF Format so, Call Function 
Module 'CONVERT_OTF' and pass "l_job_output_info-otfdata".

CALL FUNCTION 'CONVERT_OTF'
    EXPORTING
      format                = 'PDF'
    IMPORTING
      bin_filesize          = pdf_fsize
      bin_file              = p_c_ztr_reports-report_pdf
    TABLES
      otf                   = l_job_output_info-otfdata
      lines                 = lt_pdf
    EXCEPTIONS
      err_max_linewidth     = 1
      err_format            = 2
      err_conv_not_possible = 3
      OTHERS                = 4.

     
4 . You can use c_ztr_reports-report_pdf to load PDF Data 
into HTML Control by converting Xstring to binary table by 
function module 'SCMS_XSTRING_TO_BINARY'.

* Convert xstring to binary table to pass to the LOAD_DATA 
*method
  CALL FUNCTION 'SCMS_XSTRING_TO_BINARY'
    EXPORTING
      buffer     = p_c_ztr_reports-report_pdf
    TABLES
      binary_tab = lt_data.

You Will Get converted data into a internal table "lt_data".

5. Call Your Screen '100'.

 CALL SCREEN 100.

6. In PBO Module of 100 Screen.

7. Create object for HTML Container 
  Create Object g_html_container
     exporting 
      Container_name = 'PDF' " Name You have mentioned 
                               for Control Conatiner Screen.

8. Pass you defined html container to HTMl Control
    Create OBJECT g_htnl_contol
        exporting
          parent = g_html_container.

9. call intance method load data and pass your converted 
table into this method.
  * Load the HTML

  CALL METHOD g_html_control->load_data(
     EXPORTING
       type         = 'application'
       subtype      = 'pdf'
     IMPORTING
       assigned_url         = lv_url
     CHANGING
       data_table           =  lt_data
     EXCEPTIONS
       dp_invalid_parameter = 1
       dp_error_general     = 2
       cntl_error           = 3
       OTHERS               = 4 ).  
         
From this Method u will get URL in lv_url.

10. call method to show ur url at Your Screen.
 call method g_html_control->show_url( url = lv_url
                                        in_place ='X').


You Will Get your Smartform output in PDF at your screen..

Enjoy!!!!!!!!!!!!!!!