In your options page each field should be put into an options array. For Example:
When you registered your settings page you should have used a code like this:
register_setting( 'pluginPage', 'rt_fed_settings', 'rt_validate');
Once on your page where you want to call settings, use this code:
$options_fed = get_option('rt_fed_settings'); // this is calling your settings array into a variable called options_fed.
Now to call items from it you would call them just like any array items:
$options_fed['rt_fed_text_test_billing_field']
The array items were set in your plugins page, but if you want see what is in the code you can use print_r.