How can I have an amount to automatically appear in my form?

I will be having clients completing an application form residing on a third party site, whereby a payment can be made directly to the organisation that owns the site via their checkout, or select an option to direct the payment to my business.

I have the direction to my Payment Options Form (A Jotform) where a client may complete their payment via Credit Card.

The option/redirection occurs ok to my form, but no amount automatically appearing in the form

How can I setup where by the amount to be paid automatically appears in my Form.

Rob.

If your application form is a JotForm form you can pass the amount to your other payment form. Inside of this guide, you can find how to do it:

How to Automatically Pass Form Data to Another Form

Another way is to pre-populate your payment form and provide your users a link with the pre-populated amount. 

Prepopulating Fields to Your JotForm via URL Parameters

The application form is another organisations form, with option of final payment to the other organisation or my business via my Payment Options Form.
Rob
...

If the Payment Options form was created on JotForm, then my collogue's recommendation is the proper solution for your case. 

Once again, I will recommend you to check this guides:

How to Automatically Pass Form Data to Another Form

Prepopulating Fields to Your JotForm via URL Parameters