How to embed contents from external feed RSS on a page of my Hugo website (PaperMod theme)

I want to embed the content from a feed RSS of a website (I call it B) on a page of my Hugo website (I call it A).
I tried to use <iframe>, but it was unsuccessful.
It might be a solution to using the <iframe> generator from some services because it works, but sincerely I would avoid external resources if they are not strictly necessary.
Any suggestion?

Take a look at transform.Unmarshal | Hugo

Thank you.
I need help, please.

I suppose that I should be store the following content:

{{ with resources.Get "" | transform.Unmarshal }}
    {{ range .channel.item }}
        <strong>{{ .title | plainify | htmlUnescape }}</strong><br />
        <p>{{ .description | plainify | htmlUnescape }}</p>
        {{ $link := .link | plainify | htmlUnescape }}
        <a href="{{ $link }}">{{ $link }}</a><br />
    {{ end }}
{{ end }}

in a new file under /layouts/shortcodes.
Is it so, or do I need to store it in another file?

If you want to insert it in to content then a shortcode is what you need.

If you want to insert it in to a template you should use a partial instead.

I tried to create the file /layouts/shortcodes/rss.html with the previous content and recall it by inputting {{ range .channel.item }} into a post.
It doesn’t work either with {{ rss }}.
Where am I wrong?

It will be easier if you read the shortcode documentation so you understand how they work.