Embedding - iFrame

If you are using the Gallery Manager theme, then you can load the gallery's 'index.html' page into an iframe.
The Gallery Manager displays full-page galleries without a header, footer or any other content.

For example, if you create a gallery page and name it 'XYZ', Showkase will create a directory in the root Showkase directory named 'xyz'. The page you would load into the iframe would be the 'xyz/index.html' page.

Please note that loading a gallery into an iframe has certain drawbacks that are noted '2) Using an iframe' here.

As long as the page you plan to embed your gallery into is on the same domain (or subdomain) as your Showkase site, then you could use the baseUrl method of embedding your gallery (documented here) to avoid the drawbacks of using an iframe.
The folder that you would use as the baseUrl itself would be the gallery folder ('xyz' in the example above).
The baseUrl could be absolute (in the form 'http://www.example.com/showkase/xyz/) or relative (to the web page containing the baseUrl embedding code).

The web page you plan to embed your gallery into (containing the baseUrl embedding code) must be on the same domain (or subdomain) as the gallery itself due to the same-origin policy.

If the web page and gallery are not on the same domain (or subdomain), then you could implement a Cross-Origin Resource Sharing (CORS) solution by adding the following line of code to the .htaccess file in the root directory of the domain which currently hosts your gallery/Showkase site.

Header add Access-Control-Allow-Origin "*"