drupal form api for radio button help needed

Question

hi,

i have to show a custom form like below

either upload image or paste a url for the image

  O Radio button to set for image upload

  -------Input field for image upload 
  OR

  O Radio button to set image url

   --------- input field to get that url

im struggling with custom form code whether to use #type=>radio or #type=>radios

if i use type radio then there is 2 radio button will create of either choice wont work

If i use type radios how can i separate the radios as per above design

Please guide me this situation,

Nithish.