In case of you have added the reference to the SautinSoft.PdfFocus.dll by the old way (Solution Explorer->right click by "References"->Add Reference...), please add these (or newer versions) dependencies using NuGet:

		<Reference Include="System.Net.Http"/>
		<PackageReference Include="Pkcs11Interop" Version="5.1.2" />
		<PackageReference Include="Portable.BouncyCastle" Version="1.9.0" />
		<PackageReference Include="SkiaSharp" Version="2.88.7" />
		<PackageReference Include="SkiaSharp.HarfBuzz" Version="2.88.7" />
		<PackageReference Include="Svg.Skia" Version="1.0.0.18" />
		<PackageReference Include="System.IO.Packaging" Version="4.5.0" />
		<PackageReference Include="System.Text.Encoding.CodePages" Version="4.5.0" />
		<PackageReference Include="Tesseract" Version="5.2.0" />
		<PackageReference Include="Tesseract.Data.English" Version="4.0.0" />

For example, to add "System.IO.Packaging, 4.5.0:
(Solution Explorer->right click by "References"->Manage Nuget Packages...->In the tab "Browse" type "System.IO.Packaging" and find the "System.IO.Packaging", select version "4.5.0").

Detailed steps:
Windows https://sautinsoft.com/products/pdf-focus/help/net/getting-started/windows.php
Linux https://sautinsoft.com/products/pdf-focus/help/net/getting-started/convert-pdf-using-linux-csharp.php
MacOs https://sautinsoft.com/products/pdf-focus/help/net/getting-started/mac-os.php

If you will have any questions, please don't hesitate to email us at: support@sautinsoft.com