To collect applications from websites and portals that are not integrated with Traffit, you need to use the direct link to the application form. After creating a job and an application form, you can copy + paste the link to the form into multiple locations.
The link to the application form is visible in Jobs --> Job --> Post a job tab:
Depending on the website or portal, there are 2 options on how to do that:
1) Some job boards like Rocket Jobs allow it's users to put the link to their own application form in a dedicated field when filling in the job's details, like the one visible below:
The "Apply" button on the job board will link the candidate to the application form you've put here.
2) In other portals - those, that don't offer such dedicated field for that, you can copy+paste the link to the application form directly into the job description or other fields. It's a link, so every time a candidate clicks on it, he will be redirected to your application form.
You can find an example below:
No matter which of these 2 ways you choose, every candidate that applies will have an application source assigned in the system: