How to use Custom Font

Here is the App.axaml after creating your SukiUI project:

<Application xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="SukiTest.App"
             xmlns:local="using:SukiTest"
             xmlns:sukiUi="clr-namespace:SukiUI;assembly=SukiUI"
             RequestedThemeVariant="Default">
             <!-- "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options. -->

    <Application.DataTemplates>
        <local:ViewLocator/>
    </Application.DataTemplates>
  
    <Application.Styles>
        <sukiUi:SukiTheme ThemeColor="Blue" />
    </Application.Styles>
</Application>

Assuming that there exists a font file Assets/FontName-xxx.ttf and set the build action of that to AvaloniaResource

Then replace the DefaultFontFamily with your font:

<Application
    RequestedThemeVariant="Default"
    x:Class="SukiTest.App"
    xmlns="https://github.com/avaloniaui"
    xmlns:local="using:SukiTest"
    xmlns:sukiUi="clr-namespace:SukiUI;assembly=SukiUI"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <!--  "Default" ThemeVariant follows system theme variant. "Dark" or "Light" are other available options.  -->

    <Application.Resources>
        <ResourceDictionary>
            <FontFamily x:Key="DefaultFontFamily">avares://YourProject/Assets#FontName</FontFamily>
        </ResourceDictionary>
    </Application.Resources>

    <Application.DataTemplates>
        <local:ViewLocator />
    </Application.DataTemplates>

    <Application.Styles>
        <sukiUi:SukiTheme ThemeColor="Blue" />
    </Application.Styles>
</Application>