form_for and ActiveResource

Hey all,
I have a "Profile" model that I get with ActiveResource.
I have a basic form in my application to create Profiles like this:

<% form_for(:profile, :url => profiles_path) do |f| %>
<p>
  <b>First name</b><br />
  <%= text_field :profile, :first_name %>
</p>
<p>
  <b>Last name</b><br />
  <%= text_field :profile, :last_name %>
</p>

<p>
  <%= submit_tag "Create" %>
</p>
<% end %>

And in my controller I have:
def new
  @profile = Profile.new
end

When I visit /profile/new, I get this error:
undefined method `first_name' for #<Profile:0xb698fa24>

It works though if I change the "new" function this way:
def new
  @profile = Profile.new(:first_name=>'',:last_name=>'')
end

But it's not really pretty.
Is there a better way to do so?

Thanx in advance

Pat