dim condition as integer
dim rndstring as String
condition = 1 ' something here to fill the condition with 1, 2 or 3 depending on choice of radio button

If condition = 1 Then
  rndstring = Cstr(Int ((1000 - 9999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((1000 - 9999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((1000 - 9999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((1000 - 9999 + 1) * Rnd + 200)))
else If condition = 2 Then
  rndstring =  Cstr(Int ((10000 - 99999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((10000 - 99999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((10000 - 99999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((10000 - 99999 + 1) * Rnd + 200)))
else then
  rndstring = Cstr(Int ((10000 - 99999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((10000 - 99999 + 1) * Rnd + 200))) & "-" & Cstr(Int ((10000 - 99999 + 1) * Rnd + 200)))
end if

'do something with your rndstring