Simple altTemplate RSS feed - see comments for usage instructions.

Rss.cshtml

@inherits UmbracoTemplatePage
@{
    Response.ContentType = "text/xml";
    
    // The variables in this code block are the only ones you might need to change a little to get it to work    
    var blogName = "Cultiv";
    var currentUrl = string.Format("https://{0}", Request.Url.Host);

    // Find first node under the root of document type BlogOverview
    var blogNode = Model.Content.AncestorOrSelf(1).Descendants("BlogOverview").First();

    var allPosts = blogNode.Children().OrderByDescending(c => c.CreateDate);
    var latestPostDate = allPosts.Take(1).First().CreateDate.ToString("R");

	// Important: the `<?xml` opener needs to be touching the closing `}` so it is valid xml, else the first line is whitespace 
}<?xml version="1.0" encoding="UTF-8" ?><rss version="2.0" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:content="http://purl.org/rss/1.0/modules/content/">
    <channel>
        <title>@blogName</title>
        <link>@currentUrl</link>
        <pubDate>@latestPostDate</pubDate>
        <generator>umbraco</generator>
        <description></description>
        <language>en</language>
        <atom:link rel="self" type="application/rss+xml" href="@currentUrl/rss" />
        @foreach (var post in allPosts)
        {
            <item>
                <title>@post.Name</title>
                <author>info.nospamplease@@@Request.Url.Host (admin)</author>
                @Html.Raw("<link>" + currentUrl + post.Url + "</link>")
                <pubDate>@post.CreateDate.ToString("R")</pubDate>
                <guid>@(currentUrl + post.Url)</guid>
                <description>
                    @Html.Raw("<![CDATA[" + post.GetPropertyValue<string>("bodyText")
			      .Replace("/media/", currentUrl + "/media/")
			      .Replace("/blog/", currentUrl + "/blog/") + "]]>")
                </description>
                <content:encoded>
                    @Html.Raw("<![CDATA[" + post.GetPropertyValue<string>("bodyText")
			      .Replace("/media/", currentUrl + "/media/")
			      .Replace("/blog/", currentUrl + "/blog/") + "]]>")
                </content:encoded>
            </item>
        }
    </channel>    
</rss>